Chemistry Chapter 1 Questions - NCERT Class VIII

Created & Curated By S.K. Sinha

Section A: Questions

Q1.

Which of the following is NOT a characteristic of particles of matter?

(A) They are very small

(B) They have spaces between them

(D) They attract each other

Q2.

The kinetic energy of particles is maximum in:

(A) Solids

(B) Liquids

(D) All have equal kinetic energy

Q3.

The melting point of ice is:

(A) 0°C

(B) 100°C

(D) 373 K

Q4.

During evaporation, the temperature of the remaining liquid:

(A) Increases

(B) Decreases

(D) First increases then decreases

Q5.

Sublimation is the process of conversion of:

(A) Solid to liquid

(B) Liquid to gas

(D) Gas to liquid

Q6.

Which of the following substances undergo sublimation?

(A) Ice

(B) Camphor

(D) Common salt

Q7.

The process of conversion of water vapour into water is called:

(A) Evaporation

(B) Condensation

(D) Freezing

Q8.

Which state of matter has the weakest intermolecular forces?

(A) Solid

(B) Liquid

(D) Plasma

Q9.

The boiling point of water at sea level is:

(A) 100°C

(B) 273 K

(D) 212 K

Q10.

Which of the following factors does NOT affect the rate of evaporation?

(A) Temperature

(B) Surface area

(D) Color of the liquid

Q11.

Dry ice is solid:

(A) H₂O

(B) CO₂

(D) SO₂

Q12.

The temperature at which a liquid starts boiling is called:

(A) Melting point

(B) Boiling point

(D) Critical point

Q13.

In which state of matter do particles have maximum freedom of movement?

(A) Solid

(B) Liquid

(D) All states have equal freedom

Q14.

Latent heat of fusion is the energy required to:

(A) Convert liquid to gas

(B) Convert solid to liquid

(D) Heat the substance

Q15.

Which of the following has definite shape and definite volume?

(A) Gas

(B) Liquid

(D) Plasma

Q16.

The process of changing directly from gas to solid is called:

(A) Sublimation

(B) Deposition

(D) Freezing

Q17.

Which of the following statements about liquids is correct?

(A) They have definite shape

(B) They have definite volume

(D) They are incompressible under all conditions

Q18.

The SI unit of temperature is:

(A) Celsius

(B) Fahrenheit

(D) Joule

Q19.

Evaporation causes cooling because:

(A) Heat is absorbed from surroundings

(B) Heat is released to surroundings

(D) No heat transfer occurs

Q20.

Which of the following is an example of sublimation in daily life?

(A) Melting of ice cream

(B) Drying of wet clothes

(D) Boiling of water

Q21.

At what temperature do the Celsius and Kelvin scales have the same numerical value?

(A) Never

(B) 0°C

(D) -273°C

Q22.

Which factor increases the rate of evaporation?

(A) Decreasing temperature

(B) Increasing humidity

(D) Decreasing surface area

Q23.

The space between particles is maximum in:

(A) Solids

(B) Liquids

(D) All have equal spaces

Q24.

During the process of melting, the temperature:

(A) Increases continuously

(B) Decreases continuously

(D) First increases then decreases

Q25.

Which of the following best explains why solids have definite shape?

(A) Particles are very small

(B) Strong intermolecular forces keep particles in fixed positions

(D) Particles are far apart

Section B: Answers

Q1	Q2	Q3	Q4	Q5
(C)	(C)	(A)	(B)	(C)

Q6	Q7	Q8	Q9	Q10
(B)	(B)	(C)	(A)	(D)

Q11	Q12	Q13	Q14	Q15
(B)	(B)	(C)	(B)	(C)

Q16	Q17	Q18	Q19	Q20
(B)	(B)	(C)	(A)	(C)

Q21	Q22	Q23	Q24	Q25
(A)	(C)	(C)	(C)	(B)

Section C: Solutions

Q1.

Particles of matter are always in continuous motion (kinetic theory). They vibrate, rotate, and translate constantly. Option (C) is incorrect.

Q2.

Kinetic energy ∝ temperature. Gas particles move fastest, then liquid, then solid particles. Maximum kinetic energy in gases.

Q3.

Ice melts at 0°C or 273 K at standard atmospheric pressure. This is the melting point of ice.

Q4.

During evaporation, high-energy particles escape, leaving behind lower-energy particles. This decreases average kinetic energy, hence temperature decreases.

Q5.

Sublimation is direct conversion from solid to gas without passing through liquid state. Examples: dry ice, camphor, naphthalene.

Q6.

Camphor undergoes sublimation at room temperature. It directly converts from solid to gas without melting.

Q7.

Condensation is the process where gas converts to liquid when cooled. Water vapor condenses to form water droplets.

Q8.

Intermolecular forces: Solid > Liquid > Gas. Gases have weakest forces, allowing particles maximum freedom of movement.

Q9.

Water boils at 100°C (373 K) at sea level (1 atm pressure). This is the standard boiling point.

Q10.

Evaporation rate depends on temperature, surface area, humidity, and wind speed. Color of liquid doesn't affect evaporation rate.

Q11.

Dry ice is solid carbon dioxide (CO₂) that sublimates directly from solid to gas at -78.5°C.

Q12.

Boiling point is the temperature at which vapor pressure equals atmospheric pressure and liquid starts boiling throughout.

Q13.

Gas particles have maximum freedom due to weakest intermolecular forces and maximum kinetic energy.

Q14.

Latent heat of fusion is energy required to convert solid to liquid at constant temperature (melting point) without temperature change.

Q15.

Solids have definite shape and volume due to strong intermolecular forces keeping particles in fixed positions.

Q16.

Deposition is reverse of sublimation - direct conversion from gas to solid without liquid phase. Example: frost formation.

Q17.

Liquids have definite volume but take shape of container. They can flow and are nearly incompressible under normal conditions.

Q18.

Kelvin (K) is SI unit of temperature. 0 K = -273.15°C (absolute zero temperature).

Q19.

Evaporation is endothermic process. Heat energy is absorbed from surroundings to break intermolecular bonds, causing cooling effect.

Q20.

Naphthalene balls gradually disappear by sublimation - direct conversion from solid to gas at room temperature.

Q21.

Celsius and Kelvin scales never have same numerical value. K = °C + 273. They differ by constant 273.

Q22.

Increasing wind speed removes water vapor quickly, reducing humidity around liquid surface, thus increasing evaporation rate.

Q23.

Space between particles: Gas > Liquid > Solid. Gas particles are farthest apart due to high kinetic energy.

Q24.

During melting, temperature remains constant at melting point. Added heat energy breaks intermolecular bonds without temperature increase.

Q25.

Strong intermolecular forces in solids keep particles in fixed positions, giving definite shape. Particles only vibrate about mean positions.

FreeTestMaker.com

NCERT Class VIII Chemistry 25 (SCQ)

Chapter 1: Matter in Our Surroundings