Class 9 > Unit # 09: Thermal Properties of Matter > Textbook M.C.Qs

Thermal Properties of Matter Quiz

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1. Heat is the form of __________

a) Pressure b) Weight c) Energy d) All

Explanation: Heat is defined as thermal energy in transit that transfers from a body at a higher temperature to a body at a lower temperature.

2. Heat capacity is the product of mass and __________

a) Boiling point b) Freezing point c) Energy d) Specific heat of material

Explanation: Heat capacity = mass x specific heat capacity (C = m x c).

3. The amount of heat needed to convert a substance from liquid to gas is called __________

a) Heat of Vaporization b) Specific heat c) latent heat of fusion d) All

Explanation: The thermal energy required to change a liquid into gas at its boiling point without changing temperature is the heat of vaporization.

4. Thermal energy transfer required per unit mass to increase the temperature by 1°C or 1 K is called

a) Latent heat of Vaporization b) Specific heat capacity c) Latent heat of fusion d) Thermal capacity

Explanation: Specific heat capacity is defined as the quantity of heat required to raise the temperature of 1 kg of a substance through 1 K (or 1°C).

5. A fixed temperature at which a pure liquid boils is called__________.

a) melting point b) freezing point c) boiling point d) Both (a) and (b)

Explanation: The constant temperature at which a liquid turns into gas (boils) is its boiling point.

6. The melting point of ice at normal atmospheric pressure is __________.

a) 0 °C b) 0 K c) 100 °C d) Both (a) and (b)

Explanation: Ice melts at 0 °C (which is 273.15 K) under normal atmospheric pressure.

7. Thermal energy transfer required to change a solid into liquid without changing its temperature is called __________.

a) Latent heat of Fusion b) latent heat of vaporization c) latent heat of boiling d) specific heat capacity

Explanation: Latent heat of fusion is the energy required to melt a solid into a liquid at its melting point without raising its temperature.

8. Thermal energy transfer required to change a liquid into gas without changing its temperature is called

a) latent heat of freezing b) latent heat of vaporization c) latent heat of boiling d) latent heat of melting

Explanation: Latent heat of vaporization is the quantity of heat required to turn a liquid into gas at its boiling point without temperature change.

9. Evaporation can occur at __________

a) freezing point b) melting point c) boiling point d) all temperatures

Explanation: Evaporation is a surface phenomenon that takes place at all temperatures, unlike boiling which occurs at a specific point.

10. Rate of evaporation of a liquid can be increased by__________.

a) increasing humidity b) decreasing temperature c) increasing its boiling point d) decreasing atmospheric pressure

Explanation: Lowering atmospheric pressure reduces resistance against escaping vapor molecules, thereby increasing the rate of evaporation.

11. Linear thermal expansion of a solid depends upon________________.

a) increase in temperature b) original length c) properties of material d) all of these

Explanation: The change in length of a solid depends directly on its original length, the change in temperature, and the specific material's thermal expansion coefficient.