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NCERT Exemplar Class 10 Science Solutions Chapter 2 Acids Bases And Salts

NCERT Exemplar Class 10 Science Solutions Chapter 2 Acids Bases And Salts

Edited By Sumit Saini | Updated on Sep 09, 2022 01:19 PM IST | #CBSE Class 10th

Acids and bases are discussed in the NCERT exemplar Class 10 Science solutions, which tend to give hydrogen ion or hydroxide ion, respectively. When acid and base react with each other, they form water and a compound known as salt. Our experienced subject matter experts have carefully prepared the NCERT exemplar Class 10 Science chapter 2 solutions to incorporate all the detailed aspects of a solution to provide comprehensive learning. NCERT exemplar Class 10 Science chapter 2 solutions develop a sound understanding of acid, base, and salts concepts as they are thorough. The CBSE syllabus for Class 10 chapter 2 is covered in the NCERT exemplar Class 10 Science chapter 2 solutions.

This Story also Contains
  1. NCERT Exemplar Class 10 Science Solutions Chapter 2-MCQ
  2. NCERT Exemplar Class 10 Science Solutions Chapter 2-Short Answer
  3. NCERT Exemplar Class 10 Science Solutions Chapter 2-Long Answer
  4. NCERT Exemplar Solutions Class 10 Science Chapter 2 Important Topics:
  5. NCERT Class 10 Science Exemplar Solutions for Other Chapters:
  6. Features of NCERT Exemplar Class 10 Science Solutions Chapter 2 - Acids, Bases, and Salts

Also, read - NCERT Solutions for Class 10

NCERT Exemplar Class 10 Science Solutions Chapter 2-MCQ

Question:1

What happens when a solution of an acid is mixed with a solution of a base in a test tube?
(i) The temperature of the solution increases
(ii) The temperature of the solution decreases
(iii) The temperature of the solution remains the same
(iv) Salt formation takes place
(a) (i) only (b) (i) and (iii)
(c) (ii) and (iii) (d) (i) and (iv)
Answer: (d)
When an acid reacts with a base, neutralisation reaction takes place to form salt an water and it is an exothermic reaction. So, the temperature of the solution increases.

Question:2

An aqueous solution turns red litmus solution blue. Excess addition of which of the following solution would reverse the change?
(a) Baking powder
(b) Lime
(c) Ammonium hydroxide solution
(d) Hydrochloric acid
Answer: (d)
Since, the aqueous solution turns red litmus solution blue. So, it is a basic compound. An acid solution (HCl) would reverse the change. That is HCl would turn blue litmus solution to red

Question:3

During the preparation of hydrogen chloride gas on a humid day, the gas is usually passed through the guard tube containing calcium chloride. The role of calcium chloride taken in the guard tube is to
(a) absorb the evolved gas
(b) moisten the gas
(c) absorb moisture from the gas
(d) absorb Cl^{-} ions from the evolved gas
Answer:(c)
The role of calcium chloride \left ( CaCl_{2} \right ) is to absorb moisture from the gas. as calcium chloride is a good dehydrating agent.

Question:4

Which of the following salts does not contain water of crystallisation?
(a) Blue vitriol
(b) Baking soda
(c) Washing soda
(d) Gypsum
Answer: (b)
Baking soda is NaHCO_{3} (sodium hydrogen carbonate).
blue vitriol is CuSO_{4}.5H_{2}O
washing soda is Na_{2}CO_{3}.10H_{2}O
Gypsum is CuSO_{4}.2H_{2}O
The water molecules which form part of the structure of a crystal (of a salt) are called water of crystallisation. The salts which contain water of crystallisation are called hydrated salts. So, baking powder does not contain water of crystallisation.

Question:5

Sodium carbonate is a basic salt because it is a salt of
(a) strong acid and strong base
(b) weak acid and weak base
(c) strong acid and weak base
(d) weak acid and strong base

Answer: (d)
Sodium carbonate (Na_{2}CO_{3}) is the salt of weak acid carbonic acid (H_{2}CO_{3}) and a strong base sodium hydroxide (NaOH)
2NaOH+H_{2}CO_{3}\rightarrow Na_{2}CO_{3}+2H_{2}O
The salts of weak acids and strong bases give basic solutions (or alkaline solutions) having pH more than 7.

Question:6

Calcium phosphate is present in tooth enamel. Its nature is
(a) basic
(b) acidic
(c) neutral
(d) amphoteric

Answer: (a)
3Ca(OH)_{2}+2H_{3}PO_{4}\rightarrow Ca_{3}\left ( PO_{4} \right )_{2}+6H_{2}O
Calcium phosphate Ca_{3}\left ( PO_{4} \right )_{2} is basic salt, as it is a salt of weak acid (phosphoric acid) and slightly stronger base (calcium hydroxide). Also, when pH of our mouth falls below 5.5 due to eating of sweets etc., i.e., mouth is acidic, the dissolution of enamel (calcium phosphate) starts which shows that calcium phosphate is basic in nature

Question:7

A sample of soil is mixed with water and allowed to settle. The clear supernatant solution turns the pH paper yellowish-orange. Which of the following would change the colour of this pH paper to greenish-blue?
(a) Lemon juice
(b) Vinegar
(c) Common salt
(d) An antacid

Answer: (d)
As pH paper turns greenish blue for weakly basic compound and antacids contain weak base like Mg(OH)_{2}. So, an antacid would change the colour of this pH paper to greenish-blue.

Question:8

Which of the following gives the correct increasing order of acidic strength?
(a) Water <Acetic acid <Hydrochloric acid
(b) Water <Hydrochloric acid <Acetic acid
(c) Acetic acid <Water <Hydrochloric acid
(d) Hydrochloric acid <Water <Acetic acid
Answer: (a)
Hydrochloric acid is a mineral acid and ionises completely in water, that's why it is a strong acid.
Acetic acid is an organic acid and ionises only partially in water, hence, it is a weak acid. Water is neutral .
Thus, the order of acidity is
water < acetic acid < hydrochloric acid.

Question:9

If a few drops of a concentrated acid accidentally spills over the hand of a student, what should be done?
(a) Wash the hand with saline solution
(b) Wash the hand immediately with plenty of water and apply a paste of sodium hydrogencarbonate
(c) After washing with plenty of water apply solution of sodium hydroxide on the hand
(d) Neutralise the acid with a strong alkali
Answer: (b)
Wash the hand immediately with plenty of water to wash away most of the acid and then apply a paste of baking soda (NaHCO_{3}) to neutralise the little acid left. Here a strong base cannot be used to neutralise the acid due to its corrosive nature.

Question:10

Sodium hydrogencarbonate when added to acetic acid evolves a gas. Which of the following statements are true about the gas evolved?
(i) It turns lime water milky
(ii) It extinguishes a burning splinter
(iii) It dissolves in a solution of sodium hydroxide
(iv) It has a pungent odour
(a) (i) and (ii) (b) (i), (ii) and (iii)
(c) (ii), (iii) and (iv) (d) (i) and (iv)
Answer: (b)
When sodium hydrogen carbonate is added to acetic acid then carbon dioxide (CO_{2}) gas is evolved
NaHCO_{3}+CH_{3}COOH\; \rightarrow CH_{3}COONa+CO_{2}+H_{2}O
CO_{2} turns lime water milky; it is a non-supporter of combustion and is absorbed by strong alkalies like NaOH.

Question:11

Common salt besides being used in kitchen can also be used as the raw material for making
(i) washing soda
(ii) bleaching powder
(iii) baking soda
(iv) slaked lime
(a) (i) and (ii) (b) (i), (ii) and (iv)
(c) (i) and (iii) (d) (i), (iii) and (iv)
Answer: (c)
Common salt (sodium chloride) is used as a raw material for making a large number of chemicals in industry such as sodium hydroxide, washing soda, baking soda, hydrochloric acid, hydrogen, chlorine and sodium metal.

Question:12

One of the constituents of baking powder is sodium hydrogencarbonate, the other constituent is
(a) hydrochloric acid
(b) tartaric acid
(c) acetic acid
(d) sulphuric acid
Answer: (b)
Baking powder is a mixture of baking soda NaHCO_{3}, (sodium hydrogen carbonate) and a mild edible acid such as tartaric acid.

Question:13

To protect tooth decay we are advised to brush our teeth regularly. The nature of the tooth paste commonly used is
(a) acidic
(b) neutral
(c) basic
(d) corrosive
Answer: (c)
The tooth paste commonly used is basic so that the extra acid formed during tooth decay is neutralised and prevent tooth decay.
When pH of our mouth falls below 5.5 due to eating of sweets etc, (ie, our mouth is moderately acidic) then the acid becomes strong enough to attack the enamel which is made up of calcium phosphate of our teeth and corrodes it which leads to tooth decay.

Question:14

Which of the following statements is correct about an aqueous solution of an acid and of a base?
(i) Higher the pH, stronger the acid
(ii) Higher the pH, weaker the acid
(iii) Lower the pH, stronger the base
(iv) Lower the pH, weaker the base
(a) (i) and (iii) (b) (ii) and (iii)
(c) (i) and (iv) (d) (ii) and (iv)
Answer: (d)
It depends on the solution i.e., higher the pH, weaker the acid and lower the pH weaker the base.

Question:15

The pH of the gastric juices released during digestion is
(a) less than 7
(b) more than 7
(c) equal to 7
(d) equal to 0
Answer: (a)
The proteins inside the mouth establish an acidic environment. Stomach additionally secretes hydrochloric acid (pH under 7) establishing an acidic climate.
The pH of the gastric juices in the stomach is in the range of 2-5 which is somewhat acidic in nature. The acidic climate of the stomach helps the protein breaking catalysts to separate proteins without any problem. Diet consumption with a greater amount of antacid nourishments is prescribed to keep an impartial climate inside the stomach.
Our stomach produces hydrochloric acid (of pH about 1.4).

Question:16

Which of the following phenomena occur, when a small amount of acid is added to water?
(i) Ionisation
(ii) Neutralisation
(iii) Dilution
(iv) Salt formation
(a) (i) and (ii) (b) (i) and (iii)
(c) (ii) and (iii) (d) (ii) and (iv)
Answer: (b)
When water is added to an acid, their molecules dissociate to form ions.
HCl+H_{2}O\rightarrow H^{+}+Cl^{-}+H_{2}O
H_{2}O+H^{+}\rightarrow H_{3}O^{+}(Hydronium\; ion)
Mixing of an acid with water is called dilution, it results in the decrease in the concentration of ions, (H^{+},O^{-2} ) per unit volume.

Question:17

Which one of the following can be used as an acid–base indicator by a visually impared student?
(a) Litmus
(b) Turmeric
(c) Vanilla essence
(d) Petunia leaves
Answer:(c)
Vanilla essence is an olfactory indicator. So, its smell is different in acid and basic media which can be detected easily by a visually impaired student.If a basic solution is added to vanilla extract then we cannot detect the characteristic smell of vanilla extract. An acidic solution does not destroy the smell of vanilla extract.

Question:18

Which of the following substance will not give carbon dioxide on treatment with dilute acid?
(a) Marble
(b) Limestone
(c) Baking soda
(d) Lime
Answer: (d)
Lime, CaO (calcium oxide) does not evolve CO_{2} when reacted with dilute acid. Other given compounds are carbonates and hydrogen carbonates, so evolve CO_{2} with dilute acid

Question:19

Which of the following is acidic in nature?
(a) Lime juice
(b) Human blood
(c) Lime water
(d) Antacid
Answer: (a)
Lime juice is acidic in nature (pH range 2-3) because it contains citric acid.
Human blood a slightly has a alkaline range of 7.35 to 7.45
Lime water is basic in nature with a pH of 12.4
pH of Antacid typically exceeds 7.0

Question:20

In an attempt to demonstrate electrical conductivity through an electrolyte, the following apparatus (Figure 2.1) was set up. Which among the following statement(s) is(are) correct?
(i) Bulb will not glow because electrolyte is not acidic
(ii) Bulb will glow because NaOH is a strong base and furnishes ions for conduction.
(iii) Bulb will not glow because circuit is incomplete
(iv) Bulb will not glow because it depends upon the type of electrolytic solution
(a) (i) and (iii) (b) (ii) and (iv)
(c) (ii) only (c) (iv) only

Answer: (c)
An electric circuit is a path in which the electrons flow from voltage or current source. The electric current streams in a closed path.
Bulb will glow because NaOH being a strong base furnishes OH^{-} and Na^{+} ions (which are responsible for electrical conductivity).
Sodium hydroxide conducts electrons as sodium cations and hydroxyl anions. The particles move towards the two iron nails in the arrangement going about as cathode(- ) for getting cations and other as anode(+) for getting anions.

Question:21

Which of the following is used for dissolution of gold?
(a) Hydrochloric acid
(b) Sulphuric acid
(c) Nitric acid
(d) Aqua regia
Answer: (d)
Aqua-regia is used for the dissolution of gold.
Aqua-regia is a mixture of conc. HNO_{3} and conc. HCl in the ratio 1 : 3

Question:22

Which of the following is not a mineral acid?
(a) Hydrochloric acid
(b) Citric acid
(c) Sulphuric acid
(d) Nitric acid
Answer: (b)
Citric acid is an example of organic acid or edible acid
Mineral acids or inorganic acids are generally prepared from the minerals present in the earth's crust, eg.,HCl (hydrochloric acid), H_{2}SO_{4} (sulphuric acid) and HNO_{3} (nitric acid) are mineral acids.
Edible acids or organic acids are produced by plants or animals. eg, acetic acid, citric acid, lactic acid etc, are edible acids.

Question:23

Which among the following is not a base?
(a) NaOH
(b) KOH
(c) NH_{4}OH
(d) C_{2}H_{5}OH
Answer: (d)
C_{2}H_{5}OH is not a base. It is an example of an organic compound known as alcohol (ethyl alcohol) which has somewhat acidic nature. And also C_{2}H_{5}OH does not give OH^{-} ions in the solution, so it is not a base.

Question:24

Which of the following statements is not correct?
(a) All metal carbonates react with acid to give a salt, water and carbon dioxide
(b) All metal oxides react with water to give salt and acid
(c) Some metals react with acids to give salt and hydrogen
(d) Some non metal oxides react with water to form an acid
Answer: (b)
Most metal oxides are insoluble in water but some of these (e.g., Na_{2}O, CaO) dissolve in water to form alkalies not salt and acid.
\text {Metal oxide + acid }\rightarrow \text {Salt+water}
MgCO_{3} + H_{2}SO_{4} \rightarrow MgSO_{4} + H_{2}O + CO_{2}
\text {Metal oxide + water}\rightarrow \text {Base}
MgO+H_{2}O\rightarrow Mg\left ( OH \right )_{2}

Question:25

Match the chemical substances given in Column (A) with their appropriate application given in Column (B)
Column (A) Column (B)
(A) Bleaching powder (i) Preparation of glass
(B) Baking soda (ii) Production of H_{2} and Cl_{2}
(C) Washing soda (iii) Decolourisation
(D) Sodium chloride (iv) Antacid
(a) A—(ii), B—(i), C—(iv), D—(iii)
(b) A—(iii), B—(ii), C—(iv), D—(i)
(c) A—(iii), B—(iv), C—(i), D—(ii)
(d) A—(ii), B—(iv), C—(i), D—(iii)
Answer: (c)
Bleaching powder bleaches the clothes and other coloured substances.
Baking soda is a constituent of antacid.
Washing soda is used in the preparation of glass.
Sodium chloride when subjected to electrolyses gives H_{2} and Cl_{2} gases.

Question:26

Equal volumes of hydrochloric acid and sodium hydroxide solutions of same concentration are mixed and the pH of the resulting solution is checked with a pH paper. What would be the colour obtained? (You may use colour guide given in Figure 2.2)
(a) Red
(b) Yellow
(c) Yellowish green
(d) Blue

Answer: (c)
Because the resulting solution is obtained as a result of neutralisation reaction
Strong Acid + Strong Base = Neutralisation. (Ph - 7)
HCl+NaOH\rightarrow NaCl+H_{2}O
The colour of the neutral solution (with pH = 7) obtained is yellowish green.

Question:27

Which of the following is(are) true when HCl (g) is passed through water?
(i) It does not ionise in the solution as it is a covalent compound.
(ii) It ionises in the solution
(iii) It gives both hydrogen and hydroxyl ion in the solution
(iv) It forms hydronium ion in the solution due to the combination of hydrogen ion with water molecule
(a) (i) only (b) (iii) only
(c) (ii) and (iv) (d) (iii) and (iv)
Answer: (c)
When HCl is passed through water then HCl being a polar covalent compound, ionises in water as
HCl (aq)\rightarrow H^{+}+Cl^{-}
H^{+}+H_{2}O\rightarrow H_{3}O^{+}

Question:28

Which of the following statements is true for acids?
(a) Bitter and change red litmus to blue
(b) Sour and change red litmus to blue
(c) Sour and change blue litmus to red
(d) Bitter and change blue litmus to red
Answer: (c)
Acids are those chemical substances which have a sour taste and turn blue litmus solution to red.

Question:29

Which of the following are present in a dilute aqueous solution of hydrochloric acid?
(a) H_{3}O^{+}+Cl^{-}
(b) H_{3}O^{+}+OH^{-}
(c) Cl^{-}+OH^{-}
(d) unionised HCl
Answer: (a)
When acid is mixed with water, their molecules dissociate to form ions. The H^{+} ions combine with H_{2}O to form H_{3}O^{+} ions.
HCl+H_{2}O\rightarrow H^{+}+Cl^{-}+H_{2}O
H_{2}O+H^{+}\rightarrow H_{3}O^{+}\left ( \text {Hydronium ion} \right )

Question:30

Identify the correct representation of reaction occurring during chloralkali process
(a) 2NaCl(l)+2H_{2}O(l)\rightarrow 2NaOH(l)+Cl_{2}\left ( g \right )+H_{2}(g)
(b) 2NaCl(aq)+2H_{2}O(aq)\rightarrow 2NaOH(aq)+Cl_{2} \left ( g \right )+H_{2}(g)
(c) 2NaCl(aq)+2H_{2}O(l)\rightarrow 2NaOH(aq)+Cl_{2} \left ( aq \right )+H_{2}(aq)
(d) 2NaCl(aq)+2H_{2}O(l)\rightarrow 2NaOH(aq)+Cl_{2} \left ( g \right )+H_{2}(g)

Answer: (d)
2NaCl(aq)+2H_{2}O(l)\rightarrow 2NaOH(aq)+Cl_{2} \left ( g \right )+H_{2}(g)
(because state of Cl_{2} and H_{2} is gaseous,H_{2}O is liquid and that of NaCl and NaOH is aqueous)

NCERT Exemplar Class 10 Science Solutions Chapter 2-Short Answer

Question:31

Match the acids given in Column (A) with their correct source given in Column (B)
Column (A) Column (B)
(a) Lactic acid (i) Tomato
(b) Acetic acid (ii) Lemon
(c) Citric acid (iii) Vinegar
(d) Oxalic acid (iv) Curd
Answer:
We know that
Lactic acid Curd
Acetic acid Vinegar
Citric acid Lemon
Oxalic acid Tomato

Question:32

Match the important chemicals given in Column (A) with the chemical formulae given in Column (B)
Column (A) Column (B)
(a) Plaster of Paris (i) Ca\left ( OH \right )_{2}
(b) Gypsum (ii) CaSO_{4}.\frac{1}{2}H_{2}O
(c) Bleaching Powder (iii) CaSO_{4}.2H_{2}O
(d) Slaked Lime (iv) CaOCl_{2}
Answer:
We have,

A. Plaster of Paris

CaSO_{4}.0.5H_{2}O

B. Gypsum

CaSO_{4}.2H_{2}O

C. Bleaching powder

CaOCl_{2}

D. Slaked lime

Ca\left ( OH \right )_{2}

Question:33

What will be the action of the following substances on litmus paper? Dry HCl gas, Moistened NH3 gas, Lemon juice, Carbonated soft drink, Curd, Soap solution.
Answer:
(i) Dry HCl gas: No change on litmus paper
(ii) Moistened NH_{3} gas (basic): Red litmus will turn blue.
(iii) Lemon Juice (contains citric acid): Blue litmus will turn red.
(iv) Carbonated soft drinks (contains carbonic acid): Blue litmus will turn red.
(v) Curd (contains lactic acid): Blue litmus will turn red.
(vi) Soap solution (basic): Red litmus will turn blue.

Question:34

Name the acid present in ant sting and give its chemical formula. Also give the common method to get relief from the discomfort caused by the ant sting.
Answer:

Answer:
Formic acid (or methanoic acid) is present in the ant sting. The chemical formula is HCOOH. By applying some wet baking soda on the affected area, it gives relief.

Question:35

What happens when nitric acid is added to egg shell?
Answer:

Egg shells contain calcium carbonate \left ( CaCO_{3} \right ). When nitric acid is added to it, brisk effervescence due to the formation of CO_{2} gas is observed. The reaction is
CaCO_{3}(s) + 2HNO_{3}(aq)\rightarrow Ca(NO_{3})_{2} (aq) + CO_{2}(g) + H_{2}O (l)

Question:36

A student prepared solutions of (i) an acid and (ii) a base in two separate beakers. She forgot to label the solutions and litmus paper is not available in the laboratory. Since both the solutions are colourless, how will she distinguish between the two?
Answer:
In the absence of litmus, any other indicator like methyl orange, phenolphthalein, etc., can be used. Otherwise a natural indicator like turmeric can also be used. Methyl orange has the property to colour alkaline and neutral water yellow. If the water becomes acidic, it turns red immediately.

Question:37

How would you distinguish between baking powder and washing soda by heating?
Answer:
On heating \text {NaHCO}_{3} (baking soda), \text {CO}_{2} (carbon dioxide) gas is given out that turns lime water milky.
\text {2NaHCO}_{3}\rightarrow \text {Na}_{2}\text {CO}_{3}+\text {H}_{2}\text {O}+\text {CO}_{2}\text {(g)}
While on heating \text {Na}_{2}\text {CO}_{3}.\text {10H}_{2}\text {O} (washing soda) water of crystallisation is given out and the salt becomes anhydrous. The presence of water of crystallisation given as product can be tested by treating it with anhydrous \text {CuSO}_{4} (white) which becomes blue in colour in its contact.

Question:38

Salt A commonly used in bakery products on heating gets converted into another salt B which itself is used for removal of hardness of water and a gas C is evolved. The gas C when passed through lime water, turns it milky. Identify A, B and C.

Answer:
Salt A is sodium bicarbonate \text {NaHCO}_{3} (as it is used in bakery products and gives \text {Na}_{2}\text {CO}_{3} on heating).
Salt B is sodium carbonate \text {Na}_{2}\text {CO}_{3} (it is used for removal of hardness of water)
Gas C is carbon dioxide \text {CO}, (as it turns lime water milky).
\text {2NaHCO}_{3}\rightarrow \text {Na}_{2}\text {CO}_{3}+\text {H}_{2}\text {O}+\text {CO}_{2}\left ( g \right )

Question:39

In one of the industrial processes used for manufacture of sodium hydroxide, a gas X is formed as by product. The gas X reacts with lime water to give a compound Y which is used as a bleaching agent in chemical industry. Identify X and Y giving the chemical equation of the reactions involved.
Answer:
In the manufacture of sodium hydroxide, hydrogen gas and chlorine gas (X) are formed as by-product. Chlorine gas reacts with lime water to give bleaching powder, a bleaching agent.
Thus, X is chlorine gas (Cl_{2} gas)
Y is calcium oxychloride or bleaching powder (CaOCl_{2}).
The equation for the preparation of sodium hydroxide is
2NaCl (aq)+2H_{2}O (l) \rightarrow 2NaOH (aq) +Cl_{2} (g) + H_{2}(g)
Cl_{2} +Ca(OH)_{2} \rightarrow CaOCl_{2} + H_{2}O

Question:40

Fill in the missing data in the following table

Salt obtained from

Name of the salt

Formula

Base

Acid

(i) Ammonium chloride

NH_{4}Cl

NH_{4}OH

-

(ii) Copper sulphate

-

-

H_{2}SO_{4}

(iii) Sodium Chloride

NaCl

NaOH

-

(iv) Magnesium nitrate

Mg\left ( NO_{3} \right )_{2}

-

HNO_{3}

(v) Potassium sulphate

K_{2}SO_{4}

-

-

(vi) Calcium nitrate

Ca\left ( NO_{3} \right )_{2}

Ca\left ( OH \right )_{2}

-

Answer:
(i) Acid : HCl
\left [ NH_{4}OH+HCl\rightarrow NH_{4}Cl+H_{2}O \right ]
(ii) Formula : CuSO_{4}
Base : Cu\left ( OH \right )_{2}
\left [ Cu\left ( OH \right )_{2}+H_{2}SO_{4}\rightarrow CuSO_{4}+2H_{2}O \right ]
(iii) Acid : HCl
\left [ NaOH+HCl\rightarrow NaCl+H_{2}O \right ]
(iv) Base : Mg\left ( OH \right )_{2}
\left [ Mg\left ( OH \right )_{2}+2HNO_{3}-Mg\left ( NO_{3} \right )_{2}+2H_{2}O \right ]
(v) Base: KOH
Acid: H_{2}SO_{4}
\left [ 2KOH+H_{2}SO_{4}\rightarrow K_{2}SO_{4}+2H_{2}O \right ]
(vi) Acid :HNO_{3}
\left [ Ca\left ( OH \right )_{2}+2HNO_{3}\rightarrow Ca\left ( NO_{3} \right )_{2}+2H_{2}O \right ]

Question:41

What are strong and weak acids? In the following list of acids, separate strong acids from weak acids. Hydrochloric acid, citric acid, acetic acid, nitric acid, formic acid, sulphuric acid.
Answer:
Strong acid: The acid that ionises completely in aqueous solution, thus producing a high concentration of H_{3}O^{+} ions, is called a strong acid, e.g., HCl, H_{2}SO_{4}, HNO_{3} etc
Weak acid Weak acid ionises only partially in aqueous solution and thus it produces ions as well as molecules, e.g., acetic acid, carbonic acid

Strong Acid

Weak Acid

Hydrochloric acid

Citric acid

Nitric acid

Acetic acid

Sulphuric acid

Formic acid

Question:42

When zinc metal is treated with a dilute solution of a strong acid, a gas is evolved, which is utilised in the hydrogenation of oil. Name the gas evolved. Write the chemical equation of the reaction involved and also write a test to detect the gas formed.

Answer:
When zinc reacts with dilute solution of strong acid (like hydrochloric acid HCl), it forms salt and hydrogen gas is evolved which is used in hydrogenation of oil
Zn+2HCl\rightarrow ZnCl_{2}+H_{2}(g)
To test the presence of H_{2} gas when a burning splinter is brought near the mouth of the test tube, the gas burns with a pop sound.

NCERT Exemplar Class 10 Science Solutions Chapter 2-Long Answer

Question:43

In the following schematic diagram for the preparation of hydrogen gas as shown in Figure 2.3, what would happen if following changes are made?

(a) In place of zinc granules, same amount of zinc dust is taken in the test tube
(b) Instead of dilute sulphuric acid, dilute hydrochloric acid is taken
(c) In place of zinc, copper turnings are taken
(d) Sodium hydroxide is taken in place of dilute sulphuric acid and the tube is heated.

Answer:
(a) If same amount of zinc dust is taken in the test tube then the reaction will be comparatively faster and hydrogen gas will evolve with greater speed. It is because zinc dust has larger surface area than zinc granules.
(b) With dilute hydrochloric acid, almost same amount of gas is evolved.
(c) With copper turnings, hydrogen gas will not evolve because copper is less reactive, so, it does no react with dil. H_{2}SO_{4} or dil. HCl. Hence, no reaction will take place.
(d) Zinc also react with NaOH. So, if sodium hydroxide is taken, then hydrogen gas will be evolved.
Zn+2NaOH\rightarrow Na_{2}ZnO_{2}+H_{2}(g)

Question:44

For making cake, baking powder is taken. If at home your mother uses baking soda instead of baking powder in cake,
(a) how will it affect the taste of the cake and why?
(b) how can baking soda be converted into baking powder?
(c) what is the role of tartaric acid added to baking soda?

Answer:
(a) The advantage of using baking powder is that tartaric acid present in baking powder reacts with sodium carbonate \left ( Na_{2} CO_{3}\right ) produced during decomposition of NaHCO_{3} and neutralises it. If only sodium hydrogen carbonate (baking soda) is used in making cake, then sodium carbonate formed from it by the action of heat (during baking) will give a bitter taste to cake.
(b) By adding tartaric acid to baking soda we can form baking powder.
(c) Tartaric acid neutralises the sodium carbonate formed during decomposition of NaHCO_{3} hence, making the cake tasty and not bitter in taste.

Question:45

A metal carbonate X on reacting with an acid gives a gas which when passed through a solution Y gives the carbonate back. On the other hand, a gas G that is obtained at anode during electrolysis of brine is passed on dry Y, it gives a compound Z, used for disinfecting drinking water. Identity X, Y, G and Z.

Answer:
X is calcium carbonate and the gas evolved is carbon dioxide, when calcium carbonate reacts with acid
CaCO_{3}+Dil.2HCl\rightarrow CaCl_{2}+H_{2}O+CO_{2}
Solution Y is lime water Ca\left ( OH \right )_{2} because, when CO_{2} is passed through it, it gives the carbonate back as shown by the given equation.
Ca\left ( OH \right )_{2}+CO_{2}\rightarrow CaCO_{3}+H_{2}O
The gas evolved at anode during electrolysis of brine is chlorine (G)
Electrolysis 2NaCl+2H_{2}O\rightarrow 2NaOH+Cl_{2}(g)+H_{2}(g)
When chlorine gas is passed through dry Ca(OH)_{2}(Y), it produces bleaching powder (Z), used for disinfecting drinking water.
Ca(OH)_{2}+Cl_{2}\rightarrow CaOCl_{2}+H_{2}O
Hence, Z is calcium oxy-chloride \left ( CaOCl_{2} \right ) or bleaching powder.

Question:46

A dry pellet of a common base B, when kept in open absorbs moisture and turns sticky. The compound is also a by–product of chloralkali process. Identify B. What type of reaction occurs when B is treated with an acidic oxide? Write a balanced chemical equation for one such solution.

Answer:
Sodium hydroxide \left ( NaOH \right ) is commonly used base and is hygroscopic (silica gel used in packing is also hygroscopic which protects things from moisture), that is, it absorbs
moisture from the atmosphere and becomes sticky.
Thus, base B is NaOH (sodium hydroxide) It is also a by-product of chlor-alkali process.
The acidic oxide reacts with base to give salt and water.
If CO_{2} is the acidic oxide taken, then the following reaction takes place with ‘B'.

Question:47

A sulphate salt of Group 2 element of the Periodic Table is a white, soft substance, which can be moulded into different shapes by making its dough. When this compound is left in open for some time, it becomes a solid mass and cannot be used for moulding purposes. Identify the sulphate salt and why does it show such a behaviour? Give the reaction involved.
Answer:
Calcium belongs to group 2. Calcium sulphate is a white soft substance.
The sulphate salt which is used for making different shapes is plaster of Paris. Its chemical name is calcium sulphate hemihydrate \left ( CaSO_{4}.\frac{1}{2}H_{2}O \right ) . The two formula units of CaSO_{4} share one molecule of water. As a result, it is soft. When it is left open for some time, it absorbs moisture from the atmosphere and forms gypsum which is a hard solid mass.
CaSO_{4}.\frac{1}{2}H_{2}O+1\frac{1}{2}H_{2}O\rightarrow CaSO_{4}.2H_{2}O
plaster of paris Gypsum
Plaster of Paris shows such behavior because of presence half water molecule as water of crystallization. When it is left open for some time, it absorbs moisture from the atmosphere and forms gypsum, which is a hard solid mass.
So, gypsum sets as a hard solid mass and cannot be used for moulding purposes.

Question:48

Identify the compound X on the basis of the reactions given below. Also, write the name and chemical formulae of A, B and C.

Answer:

Compound X is NaOH (sodium hydroxide).
2NaOH+Zn\rightarrow Na_{2}ZnO_{2}+H_{2}(g)
NaOH+HCl\rightarrow NaCl+H_{2}O
NaOH+CH_{3}COOH\rightarrow CH_{3}COONa+H_{2}O
X is sodium hydroxide, A is sodium zincate, B is sodium chloride and C is sodium acetate.

NCERT Exemplar Solutions Class 10 Science Chapter 2 Important Topics:

The chapter on Acids, Bases, and Salts in NCERT exemplar Class 10 Science solutions chapter 2 covers the below-mentioned topics:

  • Litmus test: To identify that a given compound is an acid or base.
  • NCERT exemplar Class 10 Science solutions chapter 2 discusses the pH value, which will tell us that the given solution is acidic or basic, or neutral.
  • The aqua solution of any given compound will have acidic or basic nature by looking at its composition.
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NCERT Class 10 Science Exemplar Solutions for Other Chapters:

Features of NCERT Exemplar Class 10 Science Solutions Chapter 2 - Acids, Bases, and Salts

These Class 10 Science NCERT exemplar chapter 2 solutions provide an overview of acids, bases, and salts. The chapter gives definitions of acid, bases, and salt. Water and a compound known as salt are formed on acid and base reaction amongst each other. Class 10 students can practice and learn from these solutions for a smooth walkthrough of the chapter Acids, bases, and salts-related practice questions. The information provided in Class 10 Science NCERT exemplar solutions chapter 2 Acid, bases, and salts will be adequate for a student to develop a basic understanding of the concept. This study and practice process will help students attempt other books such as NCERT Class 10 Science, Chemistry question bank, S.Chand by Lakhmir Singh and Manjit Kaur, et cetera.

Check NCERT Solutions for questions given in the book

Must check NCERT Solution Subject Wise

Read more NCERT Notes Subject Wise

Also Check NCERT Books and NCERT Syllabus here

Frequently Asked Questions (FAQs)

1. Q1. What is the value of PH for water?

A1. The pH value of water is 7. If the pH value is less than 7 the solution will be acidic or if it is more than 7 it would be basic. 

2. Q2. A substance converts blue litmus to red. What is the nature of the substance?

A2. This litmus test is performed by acidic solution; hence, we can say the given solution is acidic in nature.

3. Q3. What is acidic strength?

A3. Tendency of any acid to give hydrogen ions is measured by its acidic strength. Acids have more acidic strength than water, and water will have more than base.

4. Q4. How important is the chapter of Acid, Base and Salts for the board examination?

A4. This chapter weighs around 3-4% of the total weightage of the paper. NCERT exemplar Class 10 Science solutions chapter 2 can help the student score high in the board examination.

5. Q5. Is the chapter Acids, Base and Salts important for Board examinations?

A5. The chapter of Acids, Base and Salts is extremely important for Board examinations as it holds around 5-7% weightage of the whole paper.

6. Q6. Is the NCERT exemplar Class 10 Science solutions chapter 2 pdf available for students to download?

A6. The NCERT exemplar Class 10 Science solutions chapter 2 pdf download feature will be activated soon for all the users. In this feature, a student will be able to download or view the pdf version of all the solutions of NCERT exemplar Class 10 Science solutions chapter 2. This will help the student to study the material in an offline mode. 

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Questions related to CBSE Class 10th

Have a question related to CBSE Class 10th ?
sadhu ashram ramgart road aligarh

If you're looking for directions or steps to reach Sadhu Ashram on Ramgart Road in Aligarh, here’s how you can get there:

Steps to Reach Sadhu Ashram, Ramgart Road, Aligarh:

  1. Starting Point:

    • Determine your starting point in Aligarh or the nearby area.

  2. Use Google Maps:

    • Open Google Maps on your phone or computer.
    • Enter "Sadhu Ashram, Ramgart Road, Aligarh" as your destination.
    • Follow the navigation instructions provided by Google Maps.

  3. By Local Transport:

    • Auto-rickshaw/Taxi: Hire an auto-rickshaw or taxi and inform the driver about your destination. Most local drivers should be familiar with Sadhu Ashram.
    • Bus: Check if there are any local buses that operate on Ramgart Road. Ask the bus conductor if the bus stops near Sadhu Ashram.

  4. Landmarks to Look For:

    • As you approach Ramgart Road, look for local landmarks that might help you confirm you’re on the right path, such as known shops, temples, or schools nearby.

  5. Ask for Directions:

    • If you're unsure, ask locals for directions to Sadhu Ashram on Ramgart Road. It's a known location in the area.

  6. Final Destination:

    • Once you reach Ramgart Road, Sadhu Ashram should be easy to spot. Look for any signage or ask nearby people to guide you to the exact location.

If you need detailed directions from a specific location or more information about Sadhu Ashram, feel free to ask

Read Complete Answer
sai raja 01 September,2024
show the previous year exams ?

Hello Aspirant,  Hope your doing great,  your question was incomplete and regarding  what exam your asking.

Read Complete Answer
SWETCHCHA MISKA 10 July,2024
as an icse student in class 10 is above 80 percent good enough to get into commerce in 11th cbse

Yes, scoring above 80% in ICSE Class 10 exams typically meets the requirements to get into the Commerce stream in Class 11th under the CBSE board . Admission criteria can vary between schools, so it is advisable to check the specific requirements of the intended CBSE school. Generally, a good academic record with a score above 80% in ICSE 10th result is considered strong for such transitions.

Read Complete Answer
Manasvini Gupta 23 July,2024
i had cleared 10th from cbse in 2022 2 years ago now i wish to apply for 12th as private candidate in 2025. can i do so?

hello Zaid,

Yes, you can apply for 12th grade as a private candidate .You will need to follow the registration process and fulfill the eligibility criteria set by CBSE for private candidates.If you haven't given the 11th grade exam ,you would be able to appear for the 12th exam directly without having passed 11th grade. you will need to give certain tests in the school you are getting addmission to prove your eligibilty.

best of luck!

Read Complete Answer
Ashvadha 03 July,2024
i had cleared 10th in 2022 from cbse can i apply for 12th as private candidate this year?

According to cbse norms candidates who have completed class 10th, class 11th, have a gap year or have failed class 12th can appear for admission in 12th class.for admission in cbse board you need to clear your 11th class first and you must have studied from CBSE board or any other recognized and equivalent board/school.

You are not eligible for cbse board but you can still do 12th from nios which allow candidates to take admission in 12th class as a private student without completing 11th.

Read Complete Answer
sadafreen356 03 July,2024
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Popular CBSE Class 10th Questions

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

Option 1)

0.34\; J

 Option 2)

0.16\; J
Option 3)

1.00\; J

 Option 4)

0.67\; J
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A person trying to lose weight by burning fat lifts a mass of 10 kg upto a height of 1 m 1000 times.  Assume that the potential energy lost each time he lowers the mass is dissipated.  How much fat will he use up considering the work done only when the weight is lifted up ?  Fat supplies 3.8×107 J of energy per kg which is converted to mechanical energy with a 20% efficiency rate.  Take g = 9.8 ms−2 :

Option 1)

2.45×10−3 kg

 Option 2)

 6.45×10−3 kg
Option 3)

 9.89×10−3 kg

 Option 4)

12.89×10−3 kg

 
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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

Option 1)

2,000 \; J - 5,000\; J

 Option 2)

200 \, \, J - 500 \, \, J
Option 3)

2\times 10^{5}J-3\times 10^{5}J

 Option 4)

20,000 \, \, J - 50,000 \, \, J
Read More

A particle is projected at 600   to the horizontal with a kinetic energy K. The kinetic energy at the highest point

Option 1)

K/2\,

 Option 2)

\; K\;
Option 3)

zero\;

 Option 4)

K/4
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In the reaction,

2Al_{(s)}+6HCL_{(aq)}\rightarrow 2Al^{3+}\, _{(aq)}+6Cl^{-}\, _{(aq)}+3H_{2(g)}

Option 1)

11.2\, L\, H_{2(g)}  at STP  is produced for every mole HCL_{(aq)}  consumed

 Option 2)

6L\, HCl_{(aq)}  is consumed for ever 3L\, H_{2(g)}      produced
Option 3)

33.6 L\, H_{2(g)} is produced regardless of temperature and pressure for every mole Al that reacts

 Option 4)

67.2\, L\, H_{2(g)} at STP is produced for every mole Al that reacts .
Read More

How many moles of magnesium phosphate, Mg_{3}(PO_{4})_{2} will contain 0.25 mole of oxygen atoms?

Option 1)

0.02

 Option 2)

3.125 × 10-2
Option 3)

1.25 × 10-2

 Option 4)

2.5 × 10-2
Read More

If we consider that 1/6, in place of 1/12, mass of carbon atom is taken to be the relative atomic mass unit, the mass of one mole of a substance will

Option 1)

decrease twice

 Option 2)

increase two fold
Option 3)

remain unchanged

 Option 4)

be a function of the molecular mass of the substance.
Read More

With increase of temperature, which of these changes?

Option 1)

Molality

 Option 2)

Weight fraction of solute
Option 3)

Fraction of solute present in water

 Option 4)

Mole fraction.
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Number of atoms in 558.5 gram Fe (at. wt.of Fe = 55.85 g mol-1) is

Option 1)

twice that in 60 g carbon

 Option 2)

6.023 × 1022
Option 3)

half that in 8 g He

 Option 4)

558.5 × 6.023 × 1023
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A pulley of radius 2 m is rotated about its axis by a force F = (20t - 5t2) newton (where t is measured in seconds) applied tangentially. If the moment of inertia of the pulley about its axis of rotation is 10 kg m2 , the number of rotations made by the pulley before its direction of motion if reversed, is

Option 1)

less than 3

 Option 2)

more than 3 but less than 6
Option 3)

more than 6 but less than 9

 Option 4)

more than 9
Read More

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