Class 9 Science NCERT MCQs Chapter 1 MATTER IN OUR SURROUNDINGS

NCERT MCQs of Class 9 (Chemistry) Chapter 1 Mater in Our Surroundings

 1) Which of the following is NOT a characteristic of matter?

A) It has mass
B) It occupies space
C) It has no volume
D) It is made up of particles
✅ Answer: C) It has no volume
📝 Explanation: Matter always has volume. Everything that has mass and occupies space is called matter.

2) The interparticle force of attraction is strongest in:
A) Solids
B) Liquids
C) Gases
D) Plasma
✅ Answer: A) Solids
📝 Explanation: The particles in solids are tightly packed, making the force of attraction stronger than in liquids or gases.

3) Which of the following is an example of diffusion?
A) Ice melting
B) Sugar dissolving in water
C) The spreading of perfume in a room
D) Boiling of water
✅ Answer: C) The spreading of perfume in a room
📝 Explanation: Diffusion is the movement of particles from a region of higher concentration to a region of lower concentration.

4) Which state of matter has no fixed shape but has a fixed volume?
A) Solid
B) Liquid
C) Gas
D) Plasma
✅ Answer: B) Liquid
📝 Explanation: Liquids take the shape of the container they are in but have a definite volume.

5) The process of conversion of liquid into gas without boiling is called:
A) Evaporation
B) Condensation
C) Sublimation
D) Melting
✅ Answer: A) Evaporation
📝 Explanation: Evaporation occurs at all temperatures when the molecules at the surface of a liquid gain enough energy to escape into the air.

6) Which of the following statements is true for gases?
A) Gases have a definite shape and volume
B) Gases can be compressed easily
C) Gases cannot flow
D) Gases have a strong intermolecular force
✅ Answer: B) Gases can be compressed easily
📝 Explanation: The particles in gases are far apart, allowing them to be compressed easily.

7) The change of state from solid to gas without becoming liquid is called:
A) Evaporation
B) Condensation
C) Sublimation
D) Melting
✅ Answer: C) Sublimation
📝 Explanation: In sublimation, a solid changes directly into gas, like camphor or dry ice.

8) Which of the following increases the rate of evaporation?
A) Decreasing temperature
B) Increasing humidity
C) Increasing surface area
D) Decreasing wind speed
✅ Answer: C) Increasing surface area
📝 Explanation: A larger surface area allows more molecules to escape, increasing the rate of evaporation.

9) Which of the following is an example of condensation?
A) Ice melting into water
B) Water vapor turning into droplets on a cold glass
C) Water boiling into steam
D) Clothes drying in the sun
✅ Answer: B) Water vapor turning into droplets on a cold glass
📝 Explanation: Condensation occurs when a gas changes back into a liquid, as seen in dew formation.

10) Which of the following is NOT a factor affecting evaporation?
A) Surface area
B) Humidity
C) Temperature
D) Color of the liquid
✅ Answer: D) Color of the liquid
📝 Explanation: The rate of evaporation depends on temperature, humidity, surface area, and wind speed but not on the liquid’s color.

11) The boiling point of water is:
A) 0°C
B) 50°C
C) 100°C
D) 150°C
✅ Answer: C) 100°C
📝 Explanation: Water boils at 100°C under normal atmospheric pressure.

12) Which state of matter has the highest energy?
A) Solid
B) Liquid
C) Gas
D) Plasma
✅ Answer: D) Plasma
📝 Explanation: Plasma is a high-energy state of matter where atoms lose electrons, forming an ionized gas.

13) Why do gases exert pressure on the walls of the container?
A) Because gas particles are at rest
B) Because gas particles move randomly and collide with walls
C) Because gases have strong intermolecular forces
D) Because gases have a fixed volume
✅ Answer: B) Because gas particles move randomly and collide with walls
📝 Explanation: The collisions of gas molecules with container walls create pressure.

14) The process by which a liquid changes into a gas at any temperature below its boiling point is:
A) Freezing
B) Evaporation
C) Sublimation
D) Condensation
✅ Answer: B) Evaporation
📝 Explanation: Evaporation happens when surface molecules of a liquid gain enough energy to escape as gas.

15) The melting point of ice is:
A) 0°C
B) 50°C
C) 100°C
D) -10°C
✅ Answer: A) 0°C
📝 Explanation: Ice melts at 0°C under normal atmospheric pressure.

16) Why does water take the shape of its container?
A) Because it has a definite shape
B) Because it has weak intermolecular forces
C) Because it has a fixed volume
D) Because it is a gas
✅ Answer: B) Because it has weak intermolecular forces
📝 Explanation: Liquids have weak intermolecular forces, allowing them to flow and take the shape of the container.

17) What happens to the temperature of a substance during its phase change?
A) It increases
B) It decreases
C) It remains constant
D) It fluctuates
✅ Answer: C) It remains constant
📝 Explanation: During phase change, energy is used to break intermolecular forces instead of raising temperature.

18) When a solid is heated, its particles:
A) Stop moving
B) Move closer together
C) Gain energy and move apart
D) Lose energy and become a gas
✅ Answer: C) Gain energy and move apart
📝 Explanation: Heating increases kinetic energy, causing particles to vibrate and move apart.

19) Why does steam cause more severe burns than boiling water?
A) Steam has a higher temperature
B) Steam contains more heat energy
C) Steam has lower heat capacity
D) Boiling water is less harmful
✅ Answer: B) Steam contains more heat energy
📝 Explanation: Steam has latent heat of vaporization, making it more dangerous than boiling water.

20) The process of solid changing into a liquid is called:
A) Freezing
B) Condensation
C) Melting
D) Sublimation
✅ Answer: C) Melting
📝 Explanation: Melting is the phase transition from solid to liquid at the melting point.

21) Which of the following is NOT a characteristic of solids?
A) Definite shape
B) Definite volume
C) Can be easily compressed
D) High density
✅ Answer: C) Can be easily compressed
📝 Explanation: Solids have a fixed shape and volume and cannot be compressed easily.

22) Which state of matter has the weakest intermolecular forces?
A) Solid
B) Liquid
C) Gas
D) Plasma
✅ Answer: C) Gas
📝 Explanation: Gas particles are far apart, leading to weak intermolecular forces.

23) Which of these substances exists in all three states naturally?
A) Iron
B) Mercury
C) Water
D) Sodium
✅ Answer: C) Water
📝 Explanation: Water can be solid (ice), liquid (water), and gas (steam).

24) The property of liquids that allows them to flow is due to:
A) High density
B) Strong intermolecular force
C) Weak intermolecular force
D) Low compressibility
✅ Answer: C) Weak intermolecular force
📝 Explanation: Liquids have weaker intermolecular forces than solids, allowing them to flow.

25) Which state of matter has the highest density?
A) Solid
B) Liquid
C) Gas
D) Plasma
✅ Answer: A) Solid
📝 Explanation: Solids have tightly packed molecules, giving them the highest density.

26) Why do gases have no fixed shape?
A) Their particles do not move
B) Their particles move freely in all directions
C) They have strong intermolecular attraction
D) They have low energy
✅ Answer: B) Their particles move freely in all directions
📝 Explanation: Gas particles are in constant random motion, allowing them to take the shape of their container.

27) What happens to the volume of a gas when pressure is increased at constant temperature?
A) Increases
B) Decreases
C) Remains the same
D) Doubles
✅ Answer: B) Decreases
📝 Explanation: According to Boyle’s Law, volume decreases as pressure increases.

28) Which of the following statements is incorrect?
A) Solids are incompressible
B) Liquids have definite shape
C) Gases can be compressed
D) Liquids take the shape of their container
✅ Answer: B) Liquids have definite shape
📝 Explanation: Liquids have no definite shape but have a definite volume.

29) Why do solids have a definite shape?
A) Because their particles are loosely packed
B) Because their particles can move freely
C) Because their particles are tightly packed and fixed in position
D) Because they have weak intermolecular forces
✅ Answer: C) Because their particles are tightly packed and fixed in position
📝 Explanation: The strong intermolecular forces keep solid particles in a fixed position.

30) Why do gases expand to fill their container?
A) Because of strong intermolecular forces
B) Because of weak intermolecular forces and high kinetic energy
C) Because they are incompressible
D) Because they are heavy
✅ Answer: B) Because of weak intermolecular forces and high kinetic energy
📝 Explanation: Gas molecules move freely, spreading out to fill any container.

31) The heat required to change a solid into a liquid at its melting point is called:
A) Latent heat of vaporization
B) Latent heat of fusion
C) Specific heat
D) Boiling heat
✅ Answer: B) Latent heat of fusion
📝 Explanation: This is the energy needed to break the bonds in a solid and turn it into a liquid.

32) At higher altitudes, water boils at:
A) 100°C
B) Above 100°C
C) Below 100°C
D) 150°C
✅ Answer: C) Below 100°C
📝 Explanation: At high altitudes, atmospheric pressure is lower, so water boils at a lower temperature.

33) Why does a liquid’s boiling point increase when pressure is increased?
A) More energy is needed to overcome intermolecular forces
B) The liquid turns into a solid
C) The liquid loses energy
D) The liquid expands
✅ Answer: A) More energy is needed to overcome intermolecular forces
📝 Explanation: Higher pressure forces molecules closer together, requiring more energy for phase change.

34) The latent heat of vaporization is the heat energy required to:
A) Change liquid to gas without a temperature change
B) Change gas to liquid
C) Freeze water into ice
D) Increase the temperature of water
✅ Answer: A) Change liquid to gas without a temperature change
📝 Explanation: This energy is absorbed to break bonds without increasing temperature.

35) Why does sweating cool the body?
A) Sweat absorbs heat and evaporates
B) Sweat releases heat
C) Sweat turns into ice
D) Sweat does not evaporate
✅ Answer: A) Sweat absorbs heat and evaporates
📝 Explanation: Evaporation removes heat from the body, cooling it down.

41) Which of the following increases the rate of evaporation?
A) High humidity
B) Low temperature
C) High wind speed
D) Small surface area
✅ Answer: C) High wind speed

42) Which of the following is NOT a characteristic of particles of matter?
A) They have spaces between them.
B) They are always at rest.
C) They attract each other.
D) They are continuously moving.

Answer: B) They are always at rest.
Explanation: Particles of matter are in constant motion. Even in solids, where movement is minimal, the particles vibrate in fixed positions.

---

43) When sugar is dissolved in water, the volume of water remains almost the same. What does this indicate?
A) Water absorbs sugar completely.
B) Sugar particles occupy spaces between water particles.
C) Sugar and water react chemically.
D) Water expands to dissolve sugar.

Answer: B) Sugar particles occupy spaces between water particles.
Explanation: This demonstrates that matter has spaces between its particles, allowing sugar particles to fit in without significantly increasing the total volume.

---

44) The process by which a solid changes directly into gas without becoming liquid is called:
A) Condensation
B) Evaporation
C) Sublimation
D) Melting

Answer: C) Sublimation
Explanation: Sublimation occurs when a solid changes directly into gas without passing through the liquid phase. Examples include camphor and dry ice.

---

45) The temperature at which a liquid starts changing into a gas is called:
A) Melting point
B) Boiling point
C) Freezing point
D) Condensation point

Answer: B) Boiling point
Explanation: The boiling point is the temperature at which a liquid turns into gas throughout the entire liquid, not just at the surface.

---

46) Which of the following statements about gases is correct?
A) They have a definite shape and volume.
B) They have a fixed shape but no fixed volume.
C) They take the shape and volume of the container.
D) They do not exert pressure on the container.

Answer: C) They take the shape and volume of the container.
Explanation: Gases have neither fixed shape nor volume. They expand to fill the entire container and take its shape.

---

47) Which of the following processes requires the absorption of heat?
A) Condensation
B) Freezing
C) Evaporation
D) Deposition

Answer: C) Evaporation
Explanation: Evaporation is the process by which liquid changes into gas by absorbing heat energy from the surroundings.

48) The rate of evaporation increases when:
A) The humidity in the air is high.
B) The surface area of the liquid is decreased.
C) The temperature is increased.
D) The air is still and not moving.

Answer: C) The temperature is increased.
Explanation: Higher temperatures provide more kinetic energy to liquid particles, making them escape faster as gas.

49) Which factor does NOT affect the rate of evaporation?
A) Surface area of the liquid
B) Humidity in the air
C) Volume of the liquid
D) Temperature

Answer: C) Volume of the liquid
Explanation: Evaporation depends on surface area, temperature, humidity, and wind speed but not on the total volume of the liquid.

---

50) Why do we feel cool when sweat evaporates from our skin?
A) The sweat absorbs moisture from the air.
B) The sweat particles move faster than before.
C) The sweat particles gain heat from our body and evaporate.
D) The sweat gets converted into ice on our skin.

Answer: C) The sweat particles gain heat from our body and evaporate.
Explanation: Evaporation is an endothermic process, meaning it absorbs heat from our skin, making us feel cool.

---

51) Why does a desert cooler work more efficiently on a hot, dry day?
A) The rate of condensation increases.
B) The rate of evaporation decreases.
C) The rate of evaporation increases.
D) The humidity in the air increases.

Answer: C) The rate of evaporation increases.
Explanation: On a hot, dry day, the air has less moisture (low humidity), allowing more evaporation, which causes a greater cooling effect.

---

52) Which property of matter is responsible for diffusion?
A) Matter is rigid.
B) Matter is continuously moving.
C) Matter is static.
D) Matter has a definite shape.

Answer: B) Matter is continuously moving.
Explanation: Diffusion occurs due to the movement of particles. The faster the movement, the quicker the diffusion.

---

53) Why does a gas exert pressure on the walls of its container?
A) Gas particles are at rest.
B) Gas particles move randomly and collide with the walls.
C) Gas particles are large and heavy.
D) Gas particles do not move.

Answer: B) Gas particles move randomly and collide with the walls.
Explanation: The continuous, random motion of gas particles leads to frequent collisions with the container walls, creating pressure.

---

54) Which process is responsible for the formation of clouds?
A) Condensation
B) Evaporation
C) Sublimation
D) Melting

Answer: A) Condensation
Explanation: Clouds form when water vapor in the air cools down and condenses into tiny water droplets.

---

55) Which of the following is an example of diffusion in gases?
A) A spoonful of sugar dissolving in water
B) The smell of perfume spreading in a room
C) Ink spreading in a beaker of water
D) Melting of ice

Answer: B) The smell of perfume spreading in a room
Explanation: In gases, diffusion occurs rapidly, allowing the fragrance of perfume to spread throughout a room.

---

56) Which one of the following conditions will increase the rate of evaporation?
A) Increasing the humidity
B) Increasing the surface area
C) Decreasing temperature
D) Keeping the liquid in a closed container

Answer: B) Increasing the surface area
Explanation: A larger surface area allows more particles to escape into the air, speeding up evaporation.

---

57) What happens to the boiling point of water when atmospheric pressure decreases?
A) It remains the same.
B) It increases.
C) It decreases.
D) It fluctuates randomly.

Answer: C) It decreases.
Explanation: At lower atmospheric pressure (like at high altitudes), water boils at a lower temperature.

---

58) What happens when a solid is heated?
A) Its particles move slower.
B) Its particles move faster and vibrate more.
C) Its particles remain at the same place.
D) The solid particles disappear instantly.

Answer: B) Its particles move faster and vibrate more.
Explanation: Heating provides energy to the particles, increasing their movement and breaking intermolecular forces.

---

59) Which of the following is the best example of a substance undergoing sublimation?
A) Ice melting into water
B) Water boiling into steam
C) Camphor disappearing when heated
D) Salt dissolving in water

Answer: C) Camphor disappearing when heated.
Explanation: Sublimation is the direct conversion of a solid into gas. Camphor and dry ice (solid CO₂) are common examples.

---

60) Which of the following correctly explains why water kept in an earthen pot stays cool?
A) The pot absorbs heat from the water.
B) The pores in the pot allow water to evaporate, causing cooling.
C) The pot freezes the water.
D) The water inside the pot undergoes condensation.

Answer: B) The pores in the pot allow water to evaporate, causing cooling.
Explanation: The tiny pores in an earthen pot enable slow evaporation of water, absorbing heat and keeping the remaining water cool.