NCERT Solutions for Class 9 Science Chapter 1 Matter in Our Surroundings (Exercise Questions)
The class 9 science matter in our surroundings question answer have been in this section. They provide clear explanations and examples to help students understand the properties and behaviour of matter in different states.
Question 1 Convert the following temperatures to the Celsius scale.
(a) 293 K
(b) 470 K.
Answer:
It is known that,
Tk = 273 + Tc
Tk = Temperature in Kelvin and
Tc = temperature in Celsius.
Therefore,
(i) Temperature (ºC) = (293 - 273) = 20 ºC
(ii) Temperature (ºC) = 470 -273 = 197 ºC
Question 2. Convert the following temperatures to the kelvin scale.
(a) 25 ºC
(b) 373 ºC
Answer:
It is known that,
TK=273+Tc
TK = Temperature in Kelvin and
TC = Temperature in Celsius.
Therefore,
(i) Temperature (K) = 273 + 25 = 298 K
(ii) Temperature (K) = 273 + 373 = 646 K
Question 3.(a) Give reason for the following observations.
- Naphthalene balls disappear with time without leaving any solid.
Answer:
Naphthalene balls disappear with time without leaving any solid because they can sublimate and directly convert into the gaseous state without leaving any solid.
Question 3.(b) Give reason for the following observations.
- We can get the smell of perfume sitting several metres away
Answer:
Perfumes contain a volatile solvent which diffuses very quickly and due to this, we can get the smell of perfume sitting several meters away.
Question 5. What is the physical state of water at-
(a) 25 ºC
(b) 0 ºC
(c) 100 ºC?
Answer:
The primary physical state of water is liquid. It converts into a gaseous state at a temperature above 100 ºC but at this temperature, it (liquid water) is in equilibrium with the gaseous state.
And below 0 oC it changes into solid and also at this temperature it (liquid water) is in equilibrium with the solid state.
Therefore;
(i) At 25 ºC water is in the liquid state
(ii) At 0 ºC it can be liquid or solid and
(iii) At 100 ºC it can be liquid or the gaseous state.
Question 6. (a) Give two reasons to justify-
- water at room temperature is a liquid.
Answer:
Water at room temperature is a liquid because-
- Below 0 ºC it converts to ice (solid)
- Above 100 ºC it converts into the gaseous state.
Question 6.(b) Give two reasons to justify-
- An iron almirah is a solid at room temperature.
Answer:
An iron almirah is a solid at room temperature because-
- At room temperature, it has a definite shape and boundaries. Also, it has a fixed volume.
- The melting point of iron is much higher than room temperature.
Question 9. Name A,B,C,D,E and F in the following diagram showing change in its state

Answer:
In the above flow chart-
A = fusion/ melting/ liquefication
B = Vaporisation/ evaporation
C = Condensation (transformation of water from a gaseous state to a liquid state)
D = Solidification (the conversion of liquid into solid is known as solidification)
E = F = Sublimation
Direct conversion of solid into gas or gas into solid without attaining the liquid phase is called sublimation.
Practice Questions for Class 9 Science Matter in Our Surroundings
These class 9 science chapter 1 matter in our surroundings question answer help students test their understanding of the concepts. By solving these NCERT Solutions for Class 9 students can strengthen their knowledge of the states of matter, properties of substances, and changes in matter. Regular practice also prepares them for exams effectively.
Question 1: Define matter. List the characteristics of particles of matter.
Answer:
Matter is anything that has mass and occupies space. Characteristics of particles of matter are
- Particles of matter are very small.
- They have space between them.
- They are constantly moving.
- They attract each other.
Question 2: Explain how evaporation causes cooling. Give two examples from daily life.
Answer:
Evaporation causes cooling because particles on the surface of a liquid absorb energy from their surroundings to change into the vapor state. This absorption of heat lowers the temperature of the surroundings.
Examples-
We feel cool when sweat evaporates from our skin.
Water kept in an earthen pot stays cool due to evaporation from the pot’s surface.
Question 3: What is sublimation? Name two substances that undergo sublimation.
Answer:
Sublimation is the process in which a solid directly changes into a gas without becoming a liquid.
Examples- Camphor and ammonium chloride.
Question 4: Select the correct statement:
(1) a small raindrop (water drop) contains about 1021 particles of water in it.
(2) The particles which make up matter are so small that we cannot see them even with a high power microscope.
(3) The evidence also shows that the particles which make up the matter are constantly ‘moving’ (they are in motion).
(4) all the above
Answer:
According to the definition of matter as given in the concept, all the given options are correct.
Hence, the answer is the option (4).
Question 5: When a glass of ice-cold water is kept open at room temperature, what observation is found?
(1) water starts to evaporate
(2) water droplets are observed on the outer walls of the glass
(3) temperature of water remains same
(4) volume of the ice cold water increases
Answer:
When a glass of water is kept at room temperature, water droplets are observed on the outer walls of the glass. This is because the water vapor present in the air when coming in contact with glass containing ice-cold water loses the heat energy, and thus, the water vapor present in the air gets condensed.
Hence, the answer is the option (2).
Approach to Solve Questions of Class 9 Science Chapter 1
To solve matter in our surroundings class 9 question answer effectively, one should build a good approach. Follow the points below to make a good strategy for solving questions from this chapter:
1. Try to learn the main ideas like the states of matter, properties of solids, liquids and gases. Also, learn the terms like diffusion, evaporation, and factors affecting the change of state.
2. It is advisable to practice drawing diagrams such as the states of matter chart, change of state by heating or cooling and cooling curve of water. This will add up to the beauty of your answer.
3. Know how to define terms like sublimation and latent heat and write clear differences between boiling and evaporation. Refer these class 9 science chapter 1 matter in our surroundings solutions for understanding these concepts better with the help of solved examples.
4. Attempt all questions from the book including in-text questions. Learn to write answers in simple, clear sentences based on textbook explanations. The matter in our surroundings ncert solutions will help you revise the topics.
5. Go through NCERT activities and real-life examples e.g., camphor sublimation, perfume diffusion as they often form the basis for application questions. After studying, close the book and try recalling answers or concepts. You can also take help from Matter in our surroundings class 9 notes.
Topics of NCERT Class 9 Science Matter in Our Surroundings
The topics covered in matter in our surroundings ncert solutions are given below. Learn the concepts through the NCERT solutions:
1.1 Physical Nature of Matter
- 1.1.1 Matter Is Made up of Particles
- 1.1.2 How Small Are These Particles of Matter?
1.2 Characteristics of Particles of Matter
- 1.2.1 Particles of Matter Have Space Between Them
- 1.2.2 Particles of Matter Are Continuously Moving
- 1.2.3 Particles of matter attracts each other
1.3 States of Matter
- 1.3.1 The Solid State
- 1.3.2 The Liquid State
- 1.3.3 The Gaseous State
1.4 Can Matter Change Its State?
- 1.4.1 Effect of Change of Temperature
- 1.4.2 Effect of Change of Pressure
1.5 Evaporation
- 1.5.1 Factors Affecting Evaporation
- 1.5.2 How Does Evaporation Cause Cooling?
Importance of Class 9 Science Chapter 1 Matter in Our Surroundings Solutions
The matter in our surroundings class 9 question answer are important because they help students to understand the basic concepts of matter, such as its states, properties, and behaviour under different conditions. Given below some points on why these solutions are important:
1. These solutions help students to understand the basic concept of matter and its different states.
2. They explain key terms like melting, evaporation, condensation, and sublimation.
3. The class 9 science matter in our surroundings question answer helps in understanding how matter behaves under different conditions of temperature and pressure.
4. Here detailed explanations are given that help in writing structured answers in exams.
5. Practising these solutions ensures better performance as most exam questions are based on NCERT.