Here is a comprehensive list of important questions with answers based on Chapter 1: Matter
in Our Surroundings for CBSE Class 9, including application-based questions to help you
prepare for exams effectively.
Q1. Define matter.
A: Matter is anything that has mass and occupies space.
Q2. Name the states of matter.
A: The three primary states of matter are solid, liquid, and gas.
Q3. What is diffusion?
A: Diffusion is the movement of particles from a region of higher concentration to a region of
lower concentration until they are evenly spread.
Q4. Why can a gas be compressed easily?
A: Gasses can be compressed easily because the particles in a gas are far apart and have
large spaces between them.
Q5. What is the basis of classification of matter into solids, liquids, and gases?
A: Matter is classified based on:
1. Intermolecular forces : Strong in solids, moderate in liquids, weak in gases.
2. Intermolecular spaces : Least in solids, more in liquids, most in gases.
3. Kinetic energy of particles : Lowest in solids, higher in liquids, highest in gases.
Q6. Why does a liquid take the shape of its container but not expand to fill it
completely?
A: Liquids have moderate intermolecular forces and spaces, allowing particles to move freely
and take the container's shape. However, their cohesive forces prevent them from spreading
indefinitely.
Q7. Explain why evaporation causes cooling.
A: During evaporation, the particles with higher kinetic energy escape the liquid's surface,
reducing the average energy of the remaining particles. This decreases the temperature,
causing cooling.
Q8. Why do gases exert pressure?
A: Gas particles move randomly and collide with the walls of the container, exerting force per
unit area. This results in pressure.
in Our Surroundings for CBSE Class 9, including application-based questions to help you
prepare for exams effectively.
Q1. Define matter.
A: Matter is anything that has mass and occupies space.
Q2. Name the states of matter.
A: The three primary states of matter are solid, liquid, and gas.
Q3. What is diffusion?
A: Diffusion is the movement of particles from a region of higher concentration to a region of
lower concentration until they are evenly spread.
Q4. Why can a gas be compressed easily?
A: Gasses can be compressed easily because the particles in a gas are far apart and have
large spaces between them.
Q5. What is the basis of classification of matter into solids, liquids, and gases?
A: Matter is classified based on:
1. Intermolecular forces : Strong in solids, moderate in liquids, weak in gases.
2. Intermolecular spaces : Least in solids, more in liquids, most in gases.
3. Kinetic energy of particles : Lowest in solids, higher in liquids, highest in gases.
Q6. Why does a liquid take the shape of its container but not expand to fill it
completely?
A: Liquids have moderate intermolecular forces and spaces, allowing particles to move freely
and take the container's shape. However, their cohesive forces prevent them from spreading
indefinitely.
Q7. Explain why evaporation causes cooling.
A: During evaporation, the particles with higher kinetic energy escape the liquid's surface,
reducing the average energy of the remaining particles. This decreases the temperature,
causing cooling.
Q8. Why do gases exert pressure?
A: Gas particles move randomly and collide with the walls of the container, exerting force per
unit area. This results in pressure.
