In the early 20th century, when the Wright brothers were working on developing a powered aeroplane, they had enough knowledge about aerodynamics, but the key challenge was how to make the aeroplane light and strong enough so that it could fly easily. After so many trials of materials, they found aluminium is the perfect metal for making a strong and light aeroplane, and that decision proved to be a game-changer. Do you ever wonder why they choose aluminium over other materials? Yes, it is because of the metallic properties of aluminium metal. Aluminium has comparatively higher conductivity, which is helpful for ignition operations. It is also lightweight and has the ability to resist corrosion, and is enough. Thus, we can say that metals and non-metals play an important role in our lives. Read on to learn more about metals and non-metals.
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NCERT Exemplar class 10 Science Chapter 3 Metals and non-metals provides a detailed explanation of the properties of metals and non-metals and the principles and theories that govern their behaviour. This chapter includes many key concepts such as the nature of materials as well as strength, conductivity, corrosion, reactivity of the materials and their practical uses. The NCERT exemplar solutions class 10 science are designed by our subject experts to offer a systematic and structured approach to these important concepts and help students develop a clear understanding of critical concepts through a series of solved examples and conceptual explanations, These NCERT exemplar solutions provide a valuable resource to enhance performance in board exams. In this article, we will discuss detailed NCERT Solutions to all the important questions which have a higher probability of being asked in further exams.
At first, the MCQ questions are covered in the Class 10 Science NCERT Exemplar Solutions Chapter 3 Metals and non-metals to enhance your knowledge. The concepts are explained in detail in Class 10 Science Chapter 3 Metals and non-metals notes available on our website.
Question 1. Which of the following properties is generally not shown by metals?
(a) Electrical conduction
(b) Sonorous in nature
(c) Dullness
(d) Ductility
Answer. (c)
Properties of metals:
1. High melting point
2. Good conductors of electricity
3. Good conductors of heat
4. High density
5. Malleable
6. Ductile
7. Sonorous nature
8. Shiny (lustrous) in nature only when it is fresh. Metals lose their shine on keeping in the air for a long time due to the formation of a thin layer of oxide, carbonate or sulphide on their surface.
Therefore option (C) is correct
Question 2. The ability of metals to be drawn into thin wire is known as
(a) ductility
(b) malleability
(c) sonorousity
(d) conductivity
Answer. (a)
(a)Ductility: The ability of metals to be drawn into thin wires.
(b)Malleability: Property which allows the metals to be hammered into thin sheets.
(c)Sonorousity: Property of metals due to which they make sound when hit with an object.
(d)Conductivity: Property of metals that allows heat to pass through them easily.
Therefore option (A) is correct
Question 3. Aluminium is used for making cooking utensils. Which of the following properties of aluminium are responsible for the same?
(i) Good thermal conductivity
(ii) Good electrical conductivity
(iii) Ductility
(iv) High melting point
(a) (i) and (ii)
(b) (i) and (iii)
(c) (ii) and (iii)
(d) (i) and (iv)
Answer. (d)
Aluminium is used for making cooking utensils. This is so because aluminium has good thermal conductivity, it is malleable (can be hammered into thin sheets), it has a light weight and high melting point.
Hence (i) and (iv) are correct
Therefore option (D) is correct
Question 4. Which one of the following metals do not react with cold as well as hot water?
(a) Na
(b) Ca
(c) Mg
(d) Fe
Answer. (d)
The reactivity of metals with water is based on the reactivity series.
Metals like (Na, K and Ca) react with cold water.
Magnesium (Mg) reacts with hot water but Zinc (Zn) and Iron (Fe) react with steam.
Metals like lead, copper, silver and gold do not react with water (or even steam).
Red hot iron reacts with steam to form iron oxide and hydrogen.
Question 5. Which of the following oxide(s) of iron would be obtained on prolonged reaction of iron with steam?
(a) FeO
(b) $\mathrm{Fe}_2 \mathrm{O}_3$
(c)$\mathrm{Fe}_3 \mathrm{O}_4$
(d)$\mathrm{Fe}_2 \mathrm{O}_3$ and $\mathrm{Fe}_3 \mathrm{O}_4$
Answer. (c)
Iron does not react directly with cold or hot water. It forms a metal oxide when steam is passed over it. When red hot iron reacts with steam it forms iron(II, III) oxide and hydrogen gas is liberated. The reaction is reversible and is shown as follows:
3Fe(s)+4$\mathrm{H}_2 \mathrm{O}$→$\mathrm{Fe}_3 \mathrm{O}_4$(s)+4$\mathrm{H}_2$(g)
Question 6. What happens when calcium is treated with water?
(i) It does not react with water
(ii) It reacts violently with water
(iii) It reacts less violently with water
(iv) Bubbles of hydrogen gas formed stick to the surface of calcium
(a) (i) and (iv)
(b) (ii) and (iii)
(c) (i) and (ii)
(d) (iii) and (iv)
Answer. (d)
Calcium reacts less violently with water and the bubbles of hydrogen gas produced stick to the surface of calcium. Due to which it floats over the water surface.
Ca(s)+2$\mathrm{H}_2 \mathrm{O}$(l)→$\mathrm{Ca} \mathrm{(OH)}_2$ (aq)+$\mathrm{H}_2$(g)
Much less heat is produced in this reaction due to which hydrogen gas formed does not catch fire.
Question 7. Generally metals react with acids to give salt and hydrogen gas. Which of the following acids does not give hydrogen gas on reacting with metals (except Mn and Mg)?
(a) $\mathrm{H}_2 \mathrm{SO}_4$
(b) HCl
(c) $\mathrm{H}\mathrm{NO}_3$
(d) All of these
Answer. (c)
Nitric acid $\mathrm{H}\mathrm{NO}_3$ does not give hydrogen gas on reacting with metals (except Manganese and Magnesium)
3Mn + 8$\mathrm{H}_2 \mathrm{NO}_3$ (dil.) → 3$\mathrm{Mn} \mathrm{(NO_3)}_2$ + 2NO + 4$\mathrm{H}_2 \mathrm{O}$
Manganese reacts with nitric acid to produce manganese(II) nitrate, nitric oxide and water.
4Mg + 10$\mathrm{H}\mathrm{NO}_3$ (dil.) → 4$\mathrm{Mg} \mathrm{(NO_3)}_2$ + $\mathrm{N}_2 \mathrm{O}$ + 5$\mathrm{H}_2 \mathrm{O}$
Manganese reacts with nitric acid to produce manganese(II) nitrate, nitric oxide and water.
4Mg + 10$\mathrm{H}\mathrm{NO}_3$(dil.) → 4$\mathrm{Mg} \mathrm{(NO_3)}_2$ + $\mathrm{N}_2 \mathrm{O}$ + 5$\mathrm{H}_2 \mathrm{O}$
Magnesium reacts with nitric acid to produce nitrate magnesium, dinitrogen monoxide and water.
Nitric acid is a strong oxidizing agent so, as soon as hydrogen gas is formed in the reaction between metal and $\mathrm{H}\mathrm{NO}_3$, it oxidizes this hydrogen to water.
Therefore option (C) is correct
Question 8. The composition of aqua-regia is
(a) Dil. $\mathrm{H}\mathrm{Cl}$: Conc. $\mathrm{H}\mathrm{NO}_3$ 3 : 1
(b) Conc.$\mathrm{H}\mathrm{Cl}$ : Dil. $\mathrm{H}\mathrm{NO}_3$ 3 : 1
(c) Conc. $\mathrm{H}\mathrm{Cl}$ : Conc.$\mathrm{H}\mathrm{NO}_3$ 3 : 1
(d) Dil.$\mathrm{H}\mathrm{Cl}$ : Dil.$\mathrm{H}\mathrm{NO}_3$ 3 : 1
Answer. (c)
Aqua regia is a mixture of nitric acid and hydrochloric acid, in a molar ratio of 1:3.
So, Conc.$\mathrm{H}\mathrm{Cl}$ and conc. $\mathrm{H}\mathrm{NO}_3$ in ratio 3 : 1 forms aqua-regia.
Aqua-regia is a highly corrosive, yellow-orange fuming liquid. It can dissolve all metals (even gold and platinum).
Question 9. Which of the following are not ionic compounds?
(i) KCl
(ii) HCl
(iii) $\mathrm{C}\mathrm{Cl}_4$
(iv) NaCl
(a) (i) and (ii)
(b) (ii) and (iii)
(c) (iii) and (iv)
(d) (i) and (iii)
Answer. (b)
Ionic compounds are neutral compounds made up of positively charged ions called cations and negatively charged ions called anions.
(i) KCl: formed by the transfer of electrons and hence ionic.
(ii) HCl: polar covalent compound (formed by sharing of electrons)
(iii) $\mathrm{C}\mathrm{Cl}_4$: is a non-polar covalent compound (formed by sharing of electrons)
(iv) NaCl: formed by the transfer of electrons and hence ionic.
Hence (ii) and (iii) are not ionic.
Therefore option (B) is correct
Question 10. Which one of the following properties is not generally exhibited by ionic compounds?
(a) Solubility in water
(b) Electrical conductivity in solid state
(c) High melting and boiling points
(d) Electrical conductivity in molten state
Answer. (b)
Properties of ionic compounds:
Can conduct electricity in molten or aqueous state only.
High melting and boiling points
Most ionic compounds are soluble in water and form aqueous solutions.
In solid states, these are non-conductors of electricity because of the absence of free ions.
The ions are held together in a fixed position by strong electrostatic force and cannot move freely.
Hence, electrical conductivity in the solid state is not generally exhibited by ionic compounds.
Therefore option (B) is correct
Question 11. Which of the following metals exist in their native state in nature?
(i) Cu
(ii) Au
(iii) Zn
(iv) Ag
(a) (i) and (ii)
(b) (ii) and (iii)
(c) (ii) and (iv)
(d) (iii) and (iv)
Answer. (c)
Gold and silver (Au and Ag) are noble metals and are very less reactive, so they are usually found in a free state (native state) in nature.
Question 12. Metals are refined by using different methods. Which of the following metals are refined by electrolytic refining?
(i) Au
(ii) Cu
(iii) Na
(iv) K
(a) (i) and (ii)
(b) (i) and (iii)
(c) (ii) and (iii)
(d) (iii) and (iv)
Answer. (a)
The method to be used for refining an impure metal depends on the nature of the metal as well as on the nature of impurities present in it.
Electrolytic refining is a process of refining a metal by the process of electrolysis.
Electrolytic refining is used for metals like Ag, Au, Cu, Zn, etc
Electrolytic refining of Cu: A large piece of impure copper is used as the anode with a thin strip of pure copper as the cathode. Copper(II) sulphate solution is the electrolyte.
Electrolytic refining of Au: A thin sheet of gold is made the cathode and a gold alloy is made the anode. Hydrochloric acid is used as an electrolyte.
Therefore option (A) is correct
Question 13. Silver articles become black on prolonged exposure to air. This is due to the formation of
(a) $\mathrm{Ag}_3\mathrm{N}$
(b) $\mathrm{Ag}_2\mathrm{O}$
(c) $\mathrm{Ag}_2\mathrm{S}$
(d) $\mathrm{Ag}_2\mathrm{S}$ and $\mathrm{Ag}_3\mathrm{N}$
Answer. (c)
Silver articles become black because silver reacts with H2S gas present in the air to form a black coating of $\mathrm{Ag}_2\mathrm{S}$.
2 Ag + $\mathrm{O}_2$ → $\mathrm{Ag}_2\mathrm{O}$
4 Ag + 2 $\mathrm{H}_2\mathrm{S}$ + 2$\mathrm{O}_2$ → 2$\mathrm{Ag}_2\mathrm{S}$ + 2$\mathrm{H}_2 \mathrm{O}$
$\mathrm{Ag}_2\mathrm{O}$ is brown in colour and $\mathrm{Ag}_2\mathrm{S}$ is black.
Therefore option (C) is correct
Question 14. Galvanisation is a method of protecting iron from rusting by coating with a thin layer of:
(a) Gallium
(b) Aluminium
(c) Zinc
(d) Silver
Answer. (c)
Galvanization is a method of protecting iron from rusting by coating it with a thin layer of zinc (Zn) metal.
Therefore option (C) is correct
Question 15. Stainless steel is very useful material for our life. In stainless steel, iron is mixed with
(a) Ni and Cr
(b) Cu and Cr
(c) Ni and Cu
(d) Cu and Au
Answer. (a)
Stainless steel: Iron (Fe) is mixed with Nickel (Ni), Chromium (Cr) and Carbon (C).
It contains approximately 17% chromium, 10% nickel and a very small amount of carbon.
Therefore option (A) is correct
Question 16. If copper is kept open in air, it slowly loses its shining brown surface and gains a green coating. It is due to the formation of
(a) $\mathrm{Cu}\mathrm{SO}_4$
(b) $\mathrm{Cu}\mathrm{CO}_3$
(c) $\mathrm{Cu}\mathrm{(NO_3)}_2$
(d) $\mathrm{Cu}\mathrm{O}$
Answer. (b)
Copper reacts with oxygen present in the air and forms a green coating on its surface due to the formation of basic copper carbonate [$\mathrm{Cu}\mathrm{CO}_3$ and $\mathrm{Cu}\mathrm{(OH)}_2$]
The reaction is given as:
2Cu + $\mathrm{O}_2$ (From air) + $\mathrm{CO}_2$ + $\mathrm{H}_2\mathrm{O}$ →$\mathrm{Cu}\mathrm{CO}_3$ + $\mathrm{Cu}\mathrm{(OH)}_2$
Basic copper carbonate(green coating)
Therefore option (B) is correct
Question 17. Generally, metals are solid in nature. Which one of the following metals is found in liquid state at room temperature?
(a) Na
(b) Fe
(c) Cr
(d) Hg
Answer. (d)
Mercury (Hg) is the only metal which is found in liquid state at room temperature
Therefore option (D) is correct
Question 18. Which of the following metals are obtained by electrolysis of their chlorides in molten state?
(i) Na
(ii) Ca
(iii) Fe
(iv) Cu
(a) (i) and (iv)
(b) (iii) and (iv)
(c) (i) and (iii)
(d) (i) and (ii)
Answer. (d)
Sodium (Na) and calcium (Ca) being highly reactive are obtained by electrolysis of their chlorides in the molten state.
During electrolysis of NaCl
NaCl→Na+(l)+Cl−(l)
At cathode: reduction of 2$\mathrm{Na}^+$(aq)+e−→Na(s)
At anode: oxidation of 2$\mathrm{Cl}^-$(aq)→Cl2(g)+2e−
Net Reaction: 2$\mathrm{Na}^+$(aq)+2$\mathrm{Cl}^-$(aq)→2Na(s)+Cl2(g)
During electrolysis of aqueous $\mathrm{Ca}\mathrm{Cl}_2$
We have,
At anode: 2$\mathrm{Cl}^-$+→$\mathrm{Cl}_2$+2e−
At anode: $\mathrm{Ca}^{2+}$+2e−→Ca(s)
Therefore option (D) is correct
Question 19. Generally, non-metals are not lustrous. Which of the following non metal is lustrous?
(a) Sulphur
(b) Oxygen
(c) Nitrogen
(d) Iodine
Answer. (d)
Shining metals are called lustrous.
Sulphur, oxygen, and nitrogen are non-lustrous.
Iodine is a non-metal having a lustrous appearance.
It has a shining surface (like that of metals).
Therefore option (D) is correct
Question 20. Which one of the following four metals would be displaced from the solution of its salts by other three metals?
(a) Mg
(b) Ag
(c) Zn
(d) Cu
Answer. (b)
We know that Ag is less reactive than Mg, Zn and Cu.
Hence Silver (Ag) metal would be displaced from the solution of its salts by the other three metals.
Mg + 2 $\mathrm{Ag}\mathrm{Cl}$ → $\mathrm{Mg}\mathrm{Cl}_2$+ 2 Ag
Zn + $\mathrm{Ag}\mathrm{Cl}$ → $\mathrm{Zn}\mathrm{Cl}_2$ + Ag
Cu + 2 $\mathrm{Ag}\mathrm{Cl}$ →$\mathrm{Cu}\mathrm{Cl}_2$ + 2 Ag
Therefore option (B) is correct
Question 21. 2 mL each of concentrated HCl, HNO3 and a mixture of concentrated HCl and concentrated HNO3 in the ratio of 3 : 1 were taken in test tubes labelled as A, B and C. A small piece of metal was put in each test tube. No change occurred in test tubes A and B but the metal got dissolved in test tube C respectively. The metal could be
(a) Al
(b) Au
(c) Cu
(d) Pt
Answer. (b)
A mixture of conc. HCl and conc. $\mathrm{H}\mathrm{NO}_3$ in the ratio of 3 : 1 is known as aqua-regia. Gold (Au) dissolve in aqua-regia.
Hence option (b) is correct.
Question 22. An alloy is
(a) an element
(b) a compound
(c) a homogeneous mixture
(d) a heterogeneous mixture
Answer. (c)
An alloy is a homogeneous mixture of different metals or a metal with one or more other element.
It is done in order to give greater strength or resistance to corrosion.
Examples: Brass, Steel, amalgam etc.
Therefore option (c) is correct
Question 23. An electrolytic cell consists of
(i) positively charged cathode
(ii) negatively charged anode
(iii) positively charged anode
(iv) negatively charged cathode
(a) (i) and (ii)
(b) (iii) and (iv)
(c) (i) and (iii)
(d) (ii) ad (iv)
Answer. (b)
An electrolytic cell consists of a positively charged anode and a negatively charged cathode.
Anode - positively charged - attracts negative ions or anions towards it
Cathode - negatively charged - attracts positive ions or cations towards it
Hence statements (iii) and (iv) are correct
Therefore option (b) is correct
Question 24. During electrolytic refining of zinc, it gets
(a) deposited on cathode
(b) deposited on anode
(c) deposited on the cathode as well as the anode
(d) remains in the solution
Answer. (a)
Electrolytic refining is a process of refining a metal by the process of electrolysis.
The impure metal is made the anode and a thin strip of pure metal is made the cathode.
The pure zinc metal deposited on the cathode is connected to the negative terminal of the battery.
Hence, Zn is deposited on the cathode.
Therefore option (a) is correct
Question 25. An element A is soft and can be cut with a knife. This is very reactive to air and cannot be kept open in air. It reacts vigorously with water. Identify the element from the following
(a) Mg
(b) Na
(c) P
(d) Ca
Answer. (b)
Given that A is soft and can be cut with a knife. This is very reactive to air and cannot be kept open in air. It reacts vigorously with water.
From the properties of the element described in the question, it can be said surely that the element is sodium (Na).
Therefore option (b) is correct
Question 26. Alloys are homogeneous mixtures of a metal with a metal or non metal. Which among the following alloys contain non-metal as one of its constituents?
(a) Brass
(b) Bronze
(c) Amalgam
(d) Steel
Answer. (d)
Alloys are homogeneous mixtures of a metal with a metal or non-metal.
Steel is an alloy which contains iron (a metal) and carbon (a non-metal).
Brass is an alloy which contains copper (a metal) and zinc (a metal).
Bronze is an alloy which contains copper (a metal) and tin (a metal).
Amalgam is formed by mixing mercury (a metal) with other metals.
Therefore option (d) is correct
Question 27. Which among the following statements is incorrect for magnesium metal?
(a) It burns in oxygen with a dazzling white flame
(b) It reacts with cold water to form magnesium oxide and evolves into hydrogen gas
(c) It reacts with hot water to form magnesium hydroxide and evolves into hydrogen gas
(d) It reacts with steam to form magnesium hydroxide and evolves into hydrogen gas
Answer. (b)
(a) When the magnesium metal burns it reacts with oxygen found in the air to form Magnesium Oxide (dazzling white flame).
$2 \mathrm{Mg}(s)+\mathrm{O}_2(g) \rightarrow 2 \mathrm{MgO}(s)+$ energy
(b) Magnesium metal does not react with cold water.
(c, d) Mg reacts with hot water and steam both. The reaction is shown below:
$\mathrm{Mg}(\mathrm{s})+\mathrm{HO}_2($ hot or steam $) \rightarrow \mathrm{Mg}(\mathrm{OH})_2+\mathrm{H}_2(\mathrm{~g})$
It gives magnesium hydroxide and hydrogen gas
Therefore option (b) is the correct answer
Question 28. Which among the following alloys contain mercury as one of its constituents?
(a) Stainless steel
(b) Alnico
(c) Solder
(d) Zinc amalgam
Answer. (d)
(a) Stainless steel: iron and carbon
(b) Alnico: Aluminium, Nickel, Cobalt and Iron plus varying levels of Copper, Titanium and Niobium.
(c) Solder: One is a soft solder, which is an alloy of tin and lead. The other is a hard solder, which is an alloy of copper and zinc.
(d) Zinc amalgam: When mercury reacts with a zinc metal, it forms the zinc amalgam
Therefore option (d) is correct
Question 29. Reaction between X and Y, forms compound Z. X loses electron and Y gains electron. Which of the following properties is not shown by Z?
(a) Has a high melting point
(b) Has a low melting point
(c) Conducts electricity in molten state
(d) Occurs as solid
Answer. (b)
During the reaction between X and Y, the compound Z is formed.
X loses electrons and Y gains electrons. Hence Z is an ionic compound.
Ionic compounds:
1 .Have a high melting point
2. Conducts electricity in molten state
3. Usually occur as solids.
Therefore option (b) is correct
Question 30. The electronic configurations of three elements X, Y and Z are X — 2, 8; Y — 2, 8, 7 and Z — 2, 8, 2. Which of the following is correct?
(a) X is a metal
(b) Y is a metal
(c) Z is a non-metal
(d) Y is a non-metal and Z is a metal
Answer. (d)
X — 2, 8: Has a complete octet, hence it is a noble gas.
Y — 2, 8, 7: It requires one electron to complete its octet.
Hence Y is a non-metal
Z — 2, 8, 2: It has a tendency to lose two electrons to complete its octet.
Hence Z is a metal
Therefore option (d) is correct
Question 31. Although metals form basic oxides, which of the following metals form an amphoteric oxide?
(a) Na
(b) Ca
(c) Al
(d) Cu
Answer. (c)
(a) Na - Sodium oxide ($\mathrm{Na}_2\mathrm{O}$) is a strongly basic oxide.
It contains an oxide ion, $\mathrm{O}_2$-, which is a very strong base and has a high tendency to combine with hydrogen ions.
(b) Ca - Calcium oxide (CaO) is basic in nature. It dissolves in water to form calcium hydroxide
(c) Al - Aluminium oxide ($\mathrm{Al}_2\mathrm{O}_3$) shows basic as well as acidic behaviour hence it is called an amphoteric oxide.
(d) Cu - Copper(II) oxide or cupric oxide (CuO)
Copper(I) oxide or cuprous oxide ($\mathrm{Cu}_2\mathrm{O}$)
Both are basic in nature
Therefore option (c) is correct
Question 32. Generally, non-metals are not conductors of electricity. Which of the following is a good conductor of electricity?
(a) Diamond
(b) Graphite
(c) Sulphur
(d) Fullerene
Answer. (b)
Graphite is a non-metal which conducts electricity.
Diamond and graphite are allotropes of Carbon (a non-metal).
A graphite crystal comprises of layers of carbon molecules or sheets of carbon particles. Each carbon atom in a graphite layer is joined to three other carbon atoms by strong covalent bonds to form flat hexagonal rings. The fourth valence electron of every carbon atom is free to move. Due to the presence of free electrons in a graphite crystal, it conducts electricity.
Therefore option (b) is correct
Question 33. Electrical wires have a coating of an insulting material. The material, generally used is
(a) Sulphur
(b) Graphite
(c) PVC
(d) All can be used
Answer. (c)
(a) Sulphur is insulating in nature. But it has a very low ignition temperature. Sulphur is also highly ductile because it is a non-metal, which makes it difficult to give it the required shape. So it is not used as a coating material for an electric wire.
(b) Graphite: A graphite crystal comprises layers of carbon molecules or sheets of carbon particles. Each carbon atom in a graphite layer is joined to three other carbon atoms by strong covalent bonds to form flat hexagonal rings. The fourth valence electron of every carbon atom is free to move. Due to the presence of free electrons in a graphite crystal, it conducts electricity.
So it is not used as a coating material for an electric wire.
(c) PVC or Polyvinyl chloride is an insulating substance. It does not allow an electric current to pass through it. The electrical wires have a covering of PVC around them.
Therefore option (c) is correct
Question 34. Which of the following non-metals is a liquid?
(a) Carbon
(b) Bromine
(c) Phosphorus
(d) Sulphur
Answer. (b)
(a) Carbon: At room temperature, it is in a solid state.
(b) Bromine: is a liquid at room temperature, solidifying at -7.2ºC.
(c) Phosphorus: is a colourless, semitransparent, soft, waxy solid at room temperature.
(d) Sulphur: At room temperature,e it is a solid
Therefore option (b) is correct
Question 35. Which of the following can undergo a chemical reaction?
(a) $\mathrm{Mg}\mathrm{SO}_4$ + Fe
(b) $\mathrm{Zn}\mathrm{SO}_4$ + Fe
(c) $\mathrm{Mg}\mathrm{SO}_4$ + Pb
(d) $\mathrm{Cu}\mathrm{SO}_4$ + Fe
Answer. (d)
(a) and (b),
Fe is less reactive than Mg and Zn, so it is impossible to replace them.
No reaction takes place.
(c)
Pb is less reactive than Mg, so it is impossible to replace Mg.
No reaction takes place.
(d)
Fe is more reactive than Cu, so it replaces Cu from $\mathrm{Cu}\mathrm{SO}_4$
Hence reaction takes place.
Therefore option (d) is correct
Question 36. Which one of the following figures correctly describes the process of electrolytic refining?
Answer. (c)
Electrolytic refining is a process of refining a metal by the process of electrolysis.
Impure metal is made anode and is connected to the positive terminal of the battery. Pure metal is made cathode and is connected to the negative terminal of the battery.
Electrolytic refining of Cu: A large piece of impure copper is used as the anode with a thin strip of pure copper as the cathode. Copper(II) sulphate solution is the electrolyte.
$\mathrm{Cu}^{2+}$ ions from the solution are deposited on the cathode while Cu from the impure anode dissolves into the solution and the impurities settle down below the anode as anode mud.
Therefore option (c) is correct
Here some short answer type questions from NCERT Exemplar Solutions for Class 10 Science Chapter 3 Metals and non-metals are given for practice. This section contains important questions that are asked in the exams.Practice short answer types from the questions below.
Question 37. Iqbal treated a lustrous, divalent element M with sodium hydroxide. He observed the formation of bubbles in reaction mixture. He made the same observations when this element was treated with hydrochloric acid. Suggest how can he identify the produced gas. Write chemical equations for both the reactions.
Answer.
M is lustrous, so the element has to be a metal.
As it reacts with NaOH, it should be a very reactive metal.
Metal + Base → Hydrogen gas
Also, the metal reacts with HCl
Metal + acid → salt + hydrogen
The divalent element M is Zn
Zn(s)+2$\mathrm{Na}\mathrm{OH}$(aq)→$\mathrm{Na}_2\mathrm{ZnO}_2$(aq)+$\mathrm{H}_2$Zn(s)+2$\mathrm{H}\mathrm{Cl}$(aq)→$\mathrm{Zn}\mathrm{Cl}_2$(aq)+$\mathrm{H}_2$
The produced gas can be identified by bringing a burning match stick near the gas. The gas burns with a pop sound, hence it is hydrogen.
Question 38. During extraction of metals, electrolytic refining is used to obtain pure metals.
(a) Which material will be used as anode and cathode for refining of silver metal by this process?
(b) Suggest a suitable electrolyte also.
(c) In this electrolytic cell, where do we get pure silver after passing electric current?
Answer. (a)
Electrolytic refining is a process of refining a metal by the process of electrolysis.
Impure metal is made anode and is connected to the positive terminal of the battery. Pure metal is made cathode and is connected to the negative terminal of the battery.
(a) Cathode: Thin strip of pure silver (It is connected to the negative terminal of the battery).
Anode: Impure, silver block (It is connected to the positive terminal of the battery).
(b) Electrolyte: any salt solution of silver like $\mathrm{Ag}\mathrm{NO}_3$ or $\mathrm{Ag}\mathrm{Cl}$
but sodium argentocyanide ($\mathrm{Na}\mathrm{[Ag(CN)}_2]$ ) is preferred.
(c) Pure metal from the electrolyte deposits on the cathode.
Question 39. Why should the metal sulphides and carbonates be converted to metal oxides in the process of extraction of metal from them?
Answer.
It is easier to obtain metals from their oxides (by reduction) than from carbonate or sulphide ores. So, before reduction, the ore must be converted into metal oxide.
Calcination: method by which a carbonate ore is converted into oxide
Roasting: method by which a sulphide ore is converted into oxide
Calcination or roasting is done depending on the nature ofthe ore
Example for calcination:
$\mathrm{Ca}\mathrm{CO}_3$→$\mathrm{Ca}\mathrm{CO}$+$\mathrm{CO}_2$
Example for roasting:
2ZnS+3$\mathrm{O}_2$→2ZnO+$\mathrm{SO}_2$
Question 40. Generally, when metals are treated with mineral acids, hydrogen gas is liberated but when metals (except Mn and Mg), treated with HNO3, hydrogen is not liberated, why?
Answer.
Nitric acid ($\left.\mathrm{HNO}_3\right)$) is a strong oxidising agent. As soon as hydrogen gas is formed in the reaction between a metal and dilute nitric acid, the nitric acid oxidises this hydrogen to water and itself gets reduced to $\mathrm{NO}_2$ or NO or $\mathrm{N}_2 \mathrm{O}$.
$\mathrm{Mg}+2 \mathrm{HNO}_3 \rightarrow \mathrm{Mg}\left(\mathrm{NO}_3\right)_2+\mathrm{H}_2$
$4 \mathrm{Zn}+10 \mathrm{HNO}_3 \rightarrow 4 \mathrm{Zn}\left(\mathrm{NO}_3\right)_2+\mathrm{N}_2 \mathrm{O}+5 \mathrm{H}_2 \mathrm{O}$
$4 \mathrm{Sn}+10 \mathrm{HNO}_3 \rightarrow 4 \mathrm{Sn}\left(\mathrm{NO}_3\right)_2+\mathrm{NH}_4 \mathrm{NO}_3+3 \mathrm{H}_2 \mathrm{O}$
$3 \mathrm{~Pb}+8 \mathrm{HNO}_3 \rightarrow 3 \mathrm{~Pb}\left(\mathrm{NO}_3\right)_2+2 \mathrm{NO}+4 \mathrm{H}_2 \mathrm{O}$
So, in the reaction of metals (except Mn and Mg), with dilute nitric acid, no hydrogen gas is evolved.
Question 41. Compound X and aluminium are used to join railway tracks.
(a) Identify the compound X
(b) Name the reaction
(c) Write down its reaction.
Answer.
(a) Compound X is iron oxide,$\mathrm{Fe}_2 \mathrm{O}_3$
(b) Thermite reaction
(c) The reaction that takes place is as follows
$\mathrm{Fe}_2 \mathrm{O}_3(s)+2 \mathrm{Al}(s) \rightarrow 2 \mathrm{Fe}(l)+\mathrm{Al}_2 \mathrm{O}_3(s)+$ Heat
Question 42. When a metal X is treated with cold water, it gives a basic salt Y with molecular formula XOH (Molecular mass = 40) and liberates a gas Z which easily catches fire. Identify X, Y and Z and also write the reaction involved
Answer.
Sodium (Na) and potassium (K) react with cold water to form basic salt NaOH and KOH respectively.
Molecular formula = XOH
Molecular mass = 40
Let the atomic weight of metal X is x
Then, molecular mass of BOH = x + 16 + 1= 40 (Given)
x = 40 – 17 = 23
Thus, metal X is sodium (Na)
Sodium reacts with water as
$2 \mathrm{Na}+2 \mathrm{H}_2 \mathrm{O} \rightarrow 2 \mathrm{NaOH}+\mathrm{H}_2$
Sodium (Na) liberates hydrogen gas (Z) in reaction with cold water.
So, Y is NaOH (sodium hydroxide)
Z Is H2 (hydrogen gas).
Question 43. A non-metal X exists in two different forms Y and Z. Y is the hardest natural substance, whereas Z is a good conductor of electricity. Identify X, Y and Z
Answer.
X exists in two different forms Y and Z
Y is the hardest natural substance, whereas Z is a good conductor of electricity
We know that diamond is the hardest natural substance, hence Y is diamond.
Now carbon (C) exists in two different forms called the allotropes of carbon. These allotropes are diamond and graphite. So X is carbon.
Z is graphite which is a good conductor of electricity.
X: Carbon
Y: Diamond
Z: Graphite
Question 44. The following reaction takes place when aluminium powder is heated with MnO2
$3 \mathrm{MnO}_2(s)+4 \mathrm{Al}(s) \rightarrow 3 \mathrm{Mn}(l)+2 \mathrm{Al}_2 \mathrm{O}_3(l)+$ Heat
(a) Is aluminium getting reduced?
(b) Is MnO2 getting oxidised?
Ans.
Oxidation is the loss of electrons and reduction is the gain of electrons.
In the reaction:
$3 \mathrm{MnO}_2(s)+4 \mathrm{Al}(s) \rightarrow 3 \mathrm{Mn}(l)+2 \mathrm{Al}_2 \mathrm{O}_3(l)+$ Heat
(a) Aluminium is getting oxidised because there is an addition of oxygen
(b) MnO2 is getting reduced because there is removal of oxygen.
Question 45. What are the constituents of solder alloy? Which property of solder makes it suitable for welding electrical wires?
Answer.
One is a soft solder, which is an alloy of tin and lead. The other is a hard solder, which is an alloy of copper and zinc.
The most commonly used solder is soft solder: an alloy of lead (Pb) and tin (Sn).
It contains 50% lead and 50% tin.
Solder is suitable for welding electrical wires because it has a low melting point. Hence, it is used for soldering (or welding) electrical wires together.
Question 46. A metal A, which is used in thermite process, when heated with oxygen gives an oxide B, which is amphoteric in nature. Identify A and B. Write down the reactions of oxide B with HCl and NaOH
Answer.
Thermite Reaction:
$4 \mathrm{Al}+3 \mathrm{O}_2 \rightarrow 2 \mathrm{Al}_2 \mathrm{O}_3(\mathrm{~s})$
Metal A is aluminum (Al) which is used in the thermite process.
Al reacts with oxygen to form aluminium oxide Al2O3 which is amphoteric in nature. So B is Al2O3
$\mathrm{Al}_2 \mathrm{O}_3(\mathrm{~s})+6 \mathrm{HCl}(\mathrm{aq}) \rightarrow 2 \mathrm{AlCl}_3(\mathrm{aq})+3 \mathrm{H}_2 \mathrm{O}(\mathrm{l})$(ii) $\mathrm{Al}_2 \mathrm{O}_3(s)+2 \mathrm{NaOH}(a q) \rightarrow 2 \mathrm{NaAlO}_2(a q)+\mathrm{H}_2 \mathrm{O}(l)$
Question 47. A metal that exists as a liquid at room temperature is obtained by heating its sulphide in the presence of air. Identify the metal and its ore and give the reaction involved.
Answer.
The only metal that exists as a liquid at room temperature is mercury (Hg).
Mercury is obtained from the sulphide ore called cinnabar (HgS).
The reaction:
Roasting
$2 \mathrm{HgS}+3 \mathrm{O}_2 \rightarrow 2 \mathrm{HgO}+2 \mathrm{SO}_2$
Heating
$$
2 \mathrm{HgO} \rightarrow 2 \mathrm{Hg}+\mathrm{O}_2
$$
Question 48. Give the formulae of the stable binary compounds that would be formed by the combination of following pairs of elements.
(a) Mg and N2
(b) Li and O2
(c) Al and Cl2
(d) K and O2
Answer.
(a)$\mathrm{Mg}_3 \mathrm{~N}_2$2 Magnesium nitride
(b) $\mathrm{Li}_2 \mathrm{O}$ Lithium oxide
(c) $\mathrm{AlCl}_3$ Aluminium chloride
(d) $\mathrm{K}_2 \mathrm{O}$ Potassium oxide
Question 49. What happens when
(a) ZnCO3 is heated in the absence of oxygen?
(b) a mixture of Cu2O and Cu2S is heated
Answer.
(a) Calcination takes place
$\mathrm{ZnCO}_3(s) \rightarrow \mathrm{ZnO}(s)+\mathrm{CO}_2(g)$
When ZnCO3 is heated in the absence of oxygen, Zinc oxide and carbon dioxide are produced.
(b) Roasting takes place
$2 \mathrm{Cu}_2 \mathrm{O}(s)+\mathrm{Cu}_2 \mathrm{~S}(s) \rightarrow 6 \mathrm{Cu}(s)+\mathrm{SO}_2(g)$
When a mixture of Cu2O and Cu2S is heated, copper metal and sulphur dioxide gas are produced
Question 50. A non-metal A is an important constituent of our food and forms two oxides B and C. Oxide B is toxic whereas C causes global warming
(a) Identify A, B and C
(b) To which Group of Periodic Table does A belong?
Answer.
(a) Non-metal A is carbon.
Two oxides are carbon monoxide and carbon dioxide.
Oxide B is toxic whereas C causes global warming
So B is carbon monoxide (CO) and C is carbon dioxide (CO2)
(b) Atomic weight of C = 6
The electronic configuration of C is 2, 4.
It is present in the 14th group (10 + valence electrons), i.e., IV A of the periodic table.
Question 51. Give two examples each of the metals that are good conductors and poor conductors of heat respectively.
Answer.
Good conductors: Silver, Bronze, Iron and copper. (All metals are good conductors of electricity)
Poor conductors: Lead and mercury.
Question 52. Name one metal and one non-metal that exist in liquid state at room temperature. Also name two metals having melting point less than 310 K (37°C)
Answer.
The only metal that exists as a liquid at room temperature is mercury (Hg).
Non-metal which exists in the liquid state at room temperature is bromine (Br).
Two metals having melting points less than 310 K (37°C) are caesium (Cs) with a melting point of 28.5°C and gallium (Ga) with a melting point of 30°C
Answer.
Element A is calcium (Ca). When it reacts with water, it forms calcium hydroxide.
$\mathrm{Ca}+\mathrm{H}_2 \mathrm{O} \rightarrow \mathrm{Ca}(\mathrm{OH})_2+\mathrm{H}_2$
Thus, compound B is calcium hydroxide [Ca(OH)2], which on heating gives CaO.
$\mathrm{Ca}(\mathrm{OH})_2 \rightarrow \mathrm{CaO}+\mathrm{H}_2 \mathrm{O}$
Thus, C is calcium oxide (CaO)
Hence the answer is:
A: Calcium
B: Ca(OH)2
C: CaO
Let, the atomic weight of alkali metal A is x. When it reacts with water it forms a compound B having molecular mass 40.
Let, the reaction is
$2 \mathrm{~A}+2 \mathrm{H}_2 \mathrm{O} \rightarrow 2 \mathrm{AOH}+\mathrm{H}_2$
Molecular mass of B = x + 16 + 1 = 40
x = 40 - 17 = 23
Hence A is Sodium (Na)
The reaction involved is:
$2 \mathrm{Na}+2 \mathrm{H}_2 \mathrm{O} \rightarrow 2 \mathrm{NaOH}+\mathrm{H}_2$
So, compound B is sodium hydroxide (NaOH)
Sodium hydroxide reacts with aluminium oxide (Al2O3) to give sodium aluminate (NaAIO2)
Thus, C is sodium aluminate NaAIO2
The reaction involved is:$\mathrm{Al}_2 \mathrm{O}_3+2 \mathrm{NaOH} \rightarrow 2 \mathrm{NaAlO}_2+\mathrm{H}_2 \mathrm{O}$
Question 55. Give the reaction involved during extraction of zinc from its ore by
(a) roasting of zinc ore
(b) calcination of zinc ore
Answer:
Roasting: method by which a sulphide ore is converted into oxide
Calcination: method by which a carbonate ore is converted into oxide
(a) Roasting of zinc ore: Sulphide ore of zinc is ZnS (zinc blende)
$2 \mathrm{ZnS}(s)+3 \mathrm{O}_2 \rightarrow 2 \mathrm{ZnO}(s)+2 \mathrm{SO}_2$
ZnO is then reduced to zinc by heating with coke (carbon)
$Z n O(s)+C(s) \rightarrow Z n(s)+C O(g)$
(b) Calcination of zinc ore: Carbonate ore of Zinc is calamine ZnCO
$\mathrm{ZnCO}_3(\mathrm{~s}) \rightarrow \mathrm{ZnO}(\mathrm{s})+\mathrm{CO}_2(\mathrm{~g})$
ZnO is then reduced to zinc by heating with coke (carbon)
$\mathrm{ZnO}(s)+C(s) \rightarrow \mathrm{Zn}(s)+\mathrm{CO}(g)$
Question 56. A metal M does not liberate hydrogen from acids but reacts with oxygen to give a black colour product. Identify M and black coloured product and also explain the reaction of M with oxygen.
Answer:
Metal M is Cu as Cu is less reactive than hydrogen. So, it does not react with acids to release hydrogen.
Cu(s)+HCl → No reaction
Copper metal does not burn in the air even on strong heating.
Copper reacts with the oxygen on prolonged heating to form a black substance, i.e., copper (Il) oxide.
$2 \mathrm{Cu}(\mathrm{s})+\mathrm{O}_2(\mathrm{~g}) \rightarrow \mathrm{CuO}(\mathrm{s})$
Question 57. An element forms an oxide A2O3 which is acidic in nature. Identify A as a metal or non-metal.
Answer:
Oxides of non-metals are acidic in nature
Oxides of metals are basic in nature
Given that the element A forms an acidic oxide, therefore, A is a non-metal.
Also, it forms an oxide A2O3 so it should have 3 valence electrons, i.e., +3 charge,
Therefore, an electronic configuration is 2, 3
Hence, A is boron and its oxide is B2O3.
Iron displaces copper from copper sulphate solution as it is a more reactive metal than copper. The reaction is as follows:
$\mathrm{Fe}(s)+\mathrm{CuSO}_4 \rightarrow \mathrm{FeSO}_4+\mathrm{Cu}$
A portion of the iron pot gets dissolved and causes holes in this process.
Iron taking part in this reaction, produces holes at places where iron metal has reacted to form iron (Il) sulphate.
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The following are the long-answer type questions that needs more practice. These NCERT Exemplar Class 10 Science Chapter 3 Metals and non-metals important questions are frequently asked in the exams. Long-answer type questions are covered to improve your subject knowledge and conceptual thinking:
(a) A is the largest constituent of air so A is nitrogen gas.
Now, when N2 is heated with H2 in a 1:3 ratio in the presence of catalyst Fe, ammonia is formed. The reaction is as follows:
$\mathrm{N}_2+\mathrm{H}_2 \rightarrow \mathrm{NH}_3$
Thus, B is ammonia gas.
Now it is given that On heating with O2, B gives an oxide C.
Ammonia, when heated with oxygen forms nitric oxide (NO).
$4 \mathrm{NH}_3+5 \mathrm{O}_2(\mathrm{~g}) \rightarrow 4 \mathrm{NO}(\mathrm{g})+6 \mathrm{H}_2 \mathrm{O}(\mathrm{g})$
NO further gets oxidised to NO2 by oxygen present in the air. The reaction is as follows:
$2 \mathrm{NO}(g)+\mathrm{O}_2(g) \rightarrow 2 \mathrm{NO}_2(g)$
Thus, C is NO2 (nitrogen dioxide)
Now it is given in the question that this oxide is passed into water in the presence of air (O2). The reaction will be:
$4 \mathrm{NO}_2+2 \mathrm{H}_2 \mathrm{O}+\mathrm{O}_2 \rightarrow 4 \mathrm{HNO}_3$
Hence nitric acid (HNO3) is produced which is a strong oxidising agent.
Thus, D is nitric acid (HNO3)
(b) The non-metal nitrogen has atomic number 7.
Its electronic configuration is 2, 5.
It belongs to group 15 or VA because N has 5 valence electrons.
Question 60. Give the steps involved in the extraction of metals of low and medium reactivity from their respective sulphide ores.
Answer:
Extraction of metals of low and medium reactivity:
1. Roasting: a respective sulphide ore is heated in air. So, metal oxide is formed.
2. Heating of metal oxide to obtain the metal
Mercury has low reactivity.
We can see the entire process for mercury (Hg) as follows:
(i) Roasting: Metal sulphide is converted into metal oxide by heating the ore strongly in the presence of excess of air.
$2 \mathrm{HgS}+3 \mathrm{O}_2 \rightarrow 2 \mathrm{HgO}+2 \mathrm{SO}_2$ (Metal oxide is formed)
(ii) Reduction: Metal oxide is then reduced to metal by heating it.
$2 \mathrm{HgO} \rightarrow 2 \mathrm{Hg}+\mathrm{O}_2$
Hence mercury is extracted.
Similarly, we can see for zinc (medium reactivity).
Roasting: $2 \mathrm{ZnS}+3 \mathrm{O}_2 \rightarrow 2 \mathrm{ZnO}+2 \mathrm{SO}_2$
Reduction: $\mathrm{ZnO}+\mathrm{C} \rightarrow \mathrm{Zn}+\mathrm{CO}$
(a) Nitric acid is a strong oxidizing agent. When aluminium (Al) is dipped in HNO3, an oxide layer of aluminium (Al2O3) is formed on the surface of the metal, which prevents it from further reaction. Thus, the reactivity of Al decreases.
(b) The affinity of Na, and Mg with oxygen is higher than that of carbon. This is because Na, and Mg metals are quite reactive and present towards the top of the reactivity series. Therefore, their oxides (Na2O, MgO) are stable. A very high temperature is required to reduce them with carbon, and at that temperature, they will form their corresponding carbides. Hence, their oxides cannot be reduced by carbon
(c) NaCl is not a conductor of electricity in a solid state whereas it does conduct electricity in an aqueous solution as well as in a molten state. Ions of NaCl are free to move in an aqueous solution to carry the charge. But in a dry or solid state, ions of NaCl cannot move to carry the charge in as they are fixed. Hence, NaCl conducts electricity in the molten state.
(d) Galvanization is a method of protecting iron from rusting by coating it with a thin layer of zinc (Zn) metal.
A thin layer of zinc is formed over the iron articles by dipping them in molten zinc. As zinc is more reactive than iron, this prevents iron from corrosion
(e) Metals like Na, K, Ca and Mg are never found in their free state in nature because these metals are quite reactive so they cannot exist in the free state and hence, they are found in nature in the form of their compounds.
Answer.
(i) $2 \mathrm{Cu}_2 \mathrm{~S}(\mathrm{~s})+3 \mathrm{O}_2(\mathrm{~g}) \rightarrow \mathrm{Cu}_2 \mathrm{O}(\mathrm{s})+2 \mathrm{SO}_2(\mathrm{~g})$
(ii)$2 \mathrm{Cu}_2 \mathrm{O}(s)+\mathrm{Cu}_2 \mathrm{~S}(s) \rightarrow 6 \mathrm{Cu}(s)+\mathrm{SO}_2(g)$
(iii) Electrolytic refining: Electrolytic refining is a process of refining a metal by the process of electrolysis.
A thick block of the impure metal is made anode (+ ve)
A thin strip of pure metal is made cathode (- ve)
CuSO4 solution is taken as an electrolyte.
At cathode:$\mathrm{Cu}^{2+}(a q)+2 e^{-} \rightarrow \mathrm{Cu}$
At anode $\mathrm{Cu}(\mathrm{s}) \rightarrow \mathrm{Cu}^{2+}(\mathrm{aq})+2 e^{-}$
(b)
Question 63. Of the three metals X, Y and Z. X reacts with cold water, Y with hot water and Z with steam only. Identify X, Y and Z and also arrange them in order of increasing reactivity.
Answer:
X is sodium or potassium (Na or K) as it reacts with cold water.
Na or K reacts violently with cold water.
$2 \mathrm{Na}+2 \mathrm{H}_2 \mathrm{O} \rightarrow 2 \mathrm{NaOH}+\mathrm{H}_2$
$2 \mathrm{~K}+2 \mathrm{H}_2 \mathrm{O} \rightarrow 2 \mathrm{KOH}+\mathrm{H}_2$
Y is magnesium (Mg) as it reacts with hot water.
$M a+2 \mathrm{H}_2 \mathrm{O} \rightarrow \mathrm{Ma}(\mathrm{OH})_2+\mathrm{H}_2$
Z is iron (Fe)
$3 \mathrm{Fe}+4 \mathrm{H}_2 \mathrm{O} \rightarrow \mathrm{Fe}_3 \mathrm{O}_4+4 \mathrm{H}_2$
Order of reactivity
Z < Y< X
Or, Fe < Mg < Na (or) K
Answer:
An element "A" burns with a golden flame in the air. So, A is sodium (Na) because it burns with a golden flame in the air.
The atomic number of B is given as 17 so B is chlorine (Cl).
When Sodium reacts with Chlorine, sodium chloride (NaCl) is formed. Hence, C is sodium chloride (NaCl)
$2 \mathrm{Na}(s)+\mathrm{Cl}_2(g) \rightarrow 2 \mathrm{NaCl}(s)$
Now it is given that an aqueous solution of product C on electrolysis gives a compound D and liberates hydrogen
Aqueous solution of NaCl, on electrolysis, gives sodium hydroxide.
Electrolysis Reaction:
The reaction at the cathode is:
$\mathrm{H}_2 \mathrm{O}(l)+2 e^{-} \rightarrow \mathrm{H}_2(g)+2 \mathrm{OH}^{-}$
The reaction at the anode is:
$\mathrm{Cl}^{-} \rightarrow \frac{1}{2} \mathrm{Cl}_2(\mathrm{~g})+1 e^{-}$
The overall reaction is:
$2 \mathrm{NaCl}(\mathrm{aq})+2 \mathrm{H}_2 \mathrm{O}(\mathrm{l}) \rightarrow 2 \mathrm{NaOH}(\mathrm{aq})+\mathrm{Cl}_2(\mathrm{~g})+\mathrm{H}_2(\mathrm{~g})$
Thus, D is sodium hydroxide (NaOH)
Question 65. Two ores A and B were taken. On heating ore A gives CO2 whereas, ore B gives SO2. What steps will you take to convert them into metals?
Answer:
We will use the following definitions:
1. Calcination: method by which a carbonate ore is converted into oxide
2. Roasting: method by which a sulphide ore is converted into oxide
3. Reduction (to convert metal oxide to metal
Given that ore A gives CO2 on heating, it must be a carbonate of moderately reactive metal like Zn.
Also given, B gives SO2, so B must be a sulphide ore, e.g., Cu2S, ZnS, HgS, etc.
A will be first subjected to calcination followed by reduction
$\mathrm{ZnCO}_3 \rightarrow \mathrm{ZnO}+\mathrm{CO}_2$(calcination)
To convert it into metal treat it with carbon
$\mathrm{ZnO}+\mathrm{C} \rightarrow \mathrm{Zn}+\mathrm{CO}$ (reduction)
B will be subjected to roasting followed by a reduction
$2 \mathrm{ZnS}+3 \mathrm{O}_2 \rightarrow 2 \mathrm{ZnO}+2 \mathrm{SO}_2$ (roasting)
$2 \mathrm{Cu}_2 \mathrm{~S}+3 \mathrm{O}_2 \rightarrow 2 \mathrm{Cu}_2 \mathrm{O}+2 \mathrm{SO}_2$ (roasting)
$2 \mathrm{HgS}+3 \mathrm{O}_2 \rightarrow 2 \mathrm{HgO}+2 \mathrm{SO}_2$ (roasting)
Metal is obtained from these oxides either by using a reducing agent like C or by auto-reduction
ZnO+C→Zn+CO (reduction)
$\mathrm{Cu}_2 \mathrm{~S}+2 \mathrm{Cu}_2 \mathrm{O} \rightarrow 6 \mathrm{Cu}+\mathrm{SO}_2$ (reduction)
Some Class 10 Science Chapter 3 NCERT Exemplar Metals and non-metals questions and answers are given below that will help you tackle complex problems. The questions below will help you evaluate your understanding of the concepts.
Question 1: Aluminium is used for making cooking utensils. Which of the following properties of aluminium are responsible for the same?
(i) Good thermal conductivity
(ii) Good electrical conductivity
(iii) Ductility
(iv) High melting point
(a) (i) and (ii)
(b) (i) and (iii)
(c) (ii) and (iii)
(d) (i) and (iv)
Answer:
Option (d) (i) and (iv)
Ductility and electrical conductivity have no connection to cooking; hence, thermal conductivity and high melting point are the answers.
Question 2: Which of the following is the correct arrange-ment of the given metals in descending order of their reactivity?
Zinc, Iron, Magnesium, Sodium
(1) Zinc > Iron > Magnesium > Sodium
(2) Sodium > Zinc > Magnesium > Iron
(3) Sodium > Magnesium > Iron > Zinc
(4) Sodium > Magnesium > Zinc > Iron
Answer:
The decreasing order of chemical reactivity is given below.
(most active) Sodium > Magnesium > Zinc > Iron (least active)
Hence, the answer is the option (4).
Question 3: Which of the following pairs will give displacement reactions?
(1) NaCl solution and copper metal
(2) MgCI2 solution and aluminium metal
(3) FeSO4 solution and silver metal
(4) AgNO3 solution and copper metal
Answer:
(a) Cu cannot displace Na → No reaction
(b) Al cannot displace Mg → No reaction
(c) Ag cannot displace Fe → No reaction
(d) Cu can displace Ag → Reaction takes place
Hence, the answer is the option (4).
Question 4: Magnetism is most beneficial for separating
(1) Non- magnetic solids from non- magnetic liquids
(2) Gases and non- metallic liquids
(3) Magnetic solids and solids such as sulfur
(4) Non- metallic solids and solids such as sulfur
Answer:
Magnetic solids and solids such as sulfur can be separated using magnetic separation.
Hence, the answer is the option (3).
Question 5: Non-metals are not lustrous. Which of the following non-metal is lustrous?
(1) Nitrogen
(2) Sulphur
(3) Iodine
(4) Oxygen
Answer:
Shining metals are also called lustrous metal. For example, gold. Non-metals such as sulphur, oxygen, nitrogen are non-lustrous but iodine is a greyish black solid and crystals have a metallic lustre.
Hence, the answer is the option (3).
To solve Class 10 Science Chapter 3 NCERT Exemplar Metals and non-metals questions, it is important to follow a systematic approach. It is recommended to strategies your study plan to solve the questions of this chapter. The following are the points that will help you build a good approach.
1. Recall the fundamental concepts like Metals are characterised as Shiny, malleable, ductile, good conductors of heat & electricity, Non-metals are dull, brittle, and poor conductors and Metalloids have properties intermediate between metals and non-metals.
2. Remember The Key Topics
A. Physical Properties
Metals:
Have high melting and boiling points (except Mercury).
They are sonorous ( they produce sound when struck).
Non-Metals:
Have low melting and boiling points (except diamond).
They exist in all states (solid, liquid, gas).
B. Chemical Properties
Reactivity Series:
Memorize the series $\mathrm{K}>\mathrm{Na}>\mathrm{Ca}>\mathrm{Mg}>\mathrm{Al}>\mathrm{Zn}>\mathrm{Fe}>\mathrm{Pb}>[\mathrm{H}]>\mathrm{Cu}>\mathrm{Hg}>\mathrm{Ag}>\mathrm{Au}$.
Displacement Reactions is defined as more reactive metal displaces a less reactive one from its compound.
3. When metals and non-metals reacts with oxygen Metals form basic oxides and Non-metals form acidic oxides. To understand these concepts in details follow Class 10 Science Chapter 3 Metals and non-metals notes.
4. Some metals (Al, Zn) react with bases to produce hydrogen gas.
5. Learning about these processes is essential because questions are often asken from them
Extraction of Metals:
Electrolytic reduction for highly reactive metals (e.g., Al).
Roasting/Calcination for moderately reactive metals (e.g., Zn).
Smelting with reducing agents (e.g., Fe with Coke).
Corrosion:
Rusting of iron $4 \mathrm{Fe}+3 \mathrm{O}_2+2 x \mathrm{H}_2 \mathrm{O} \rightarrow 2 \mathrm{Fe}_2 \mathrm{O}_3 . x \mathrm{H}_2 \mathrm{O}$.
Prevention: Galvanisation, painting, alloying.
6. Label diagrams in Electrolytic refining, reactivity series. Practice the equations of writing balanced chemical equations for reactions.
7. Practice again and again, as it will help in mastering NCERT Exemplar class 10 Science Chapter 3 Metals and non-metals . Start with simpler problems then gradually move to difficult ones. Questions from this chapterare asked directly in the CBSE and State board exams.
NCERT Exemplar Class 10 Science Solutions Chapter 3 covers the topics-
1. Physical properties
i) Metals
ii) Non-metals
2. Chemical Properties of Metals
i) What happens when metal are burnt in air
ii)What happens when metal react with water
iii) What happens when metal reacts with acids
iv) How do metals react with solutions of other metal salts
v) The reactivity series
3. How do metals and non-metals react?
i) Properties of ionic compounds
4. Occurance of metals
NCERT Exemplar Solutions for Class 10 Science Chapter 3 Metals and non-metals helps students to understand the physical and chemical properties of elements. Given below some points on the advantages of these solutions:
These chapter-wise solutions offer clear, detailed explanations to higher-level questions, helping students strengthen conceptual understanding and improve exam performance.
The NCERT Solutions for all Class 10 science chapters are given below-
Students can refer to the links given below for the NCERT subject-wise solutions:
Students can refer to the links given below for the NCERT subject-wise notes:
Students can refer to the links given below for the NCERT Books and Syllabus of class 10:
Frequently Asked Questions (FAQs)
Properties of metals: Good conductor of heat and electricity, ductile, malleable and shiny surface (lustre).
Properties of non-metals: poor conductors of heat and electricity, brittle and lack of lustre.
Metals have free electrons in their metallic structure when a voltage is applied to these free electrons, can easily move with an electrical charge.
Mercury (Hg) is a metal but it is liquid at room temperature so all metals are not solid at room temperature.
Non-metals do not have any free electrons, they are tightly bound with close atoms or molecules therefore they can not easily move with electrical charge.
Applications of metals in daily life:
The chapter Metals and Non-metals is of extreme importance in the context of the board examination as it accounts for atlease 8-10% of the total marks of the paper. NCERT exemplar Class 10 Science solutions chapter 3 provides detailed solutions to all the problems related to this chapter.
Class 10 Science NCERT Exemplar Solutions Chapter 3 Metals and non-metals provide step-by-step explanations of properties, reactions, and uses of metals and non-metals to help students understand key concepts easily.
In NCERT, a non-metal is an element that is generally brittle, non-lustrous, poor conductor of heat and electricity, and tends to gain electrons during chemical reactions.
Understanding metals and non-metals is crucial because these elements make up most of the materials we use in our daily lives. Knowledge of their properties helps students comprehend various scientific principles and encourages critical thinking regarding material selection in different applications, enhancing overall scientific literacy.
The reactivity series ranks metals based on their reactivity, which is an important concept for understanding how different metals react with water, acids, and non-metals. This helps predict the outcomes of chemical reactions, enabling students to grasp the significance of each metal's position in the series.
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Download the Class 10 competency-based Questions from the article given below
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https://school.careers360.com/boards/cbse/cbse-class-10-science-competency-based-questions-2026
Dear Student,
The first phase of the CBSE Class 10th 2026 LOC submission has ended on March 31, 2026. As per the notice, CBSE has set April 16 to April 20, 2026, as the main period for schools to submit the LOC and pay the exam fees .
Check for
A block of mass 0.50 kg is moving with a speed of 2.00 ms-1 on a smooth surface. It strikes another mass of 1.00 kg and then they move together as a single body. The energy loss during the collision is
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An athlete in the olympic games covers a distance of 100 m in 10 s. His kinetic energy can be estimated to be in the range
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A particle is projected at 600 to the horizontal with a kinetic energy . The kinetic energy at the highest point
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In the reaction,
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How many moles of magnesium phosphate, will contain 0.25 mole of oxygen atoms?
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0.02 |
Option 2)
3.125 × 10-2 |
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1.25 × 10-2 |
Option 4)
2.5 × 10-2 |
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