HEAT KBSM

Diagram shows a thermometer. Which modification will increase the sensitivity of the thermometer?

• Using a longer capillary tube

• Using a glass stem with a thicker wall

• Using a bulb with a thicker wall

• Using a narrower bore of capillary tube

Answer explanation

Capillary with narrow bore produces a greater change in the length of the mercury column.

Diagram shows a heating curve for a solid substance. Heat absorbed to overcome the bonding of molecules at...

• P and R

• Q and S

• R and S

• Q and R

Answer explanation

During phase change, the energy supplied is used only to separate the molecules ; no part of it is used to increase the kinetic energy of the molecules. So its temperature will not rise, since kinetic energy of molecules remains the same.

Diagram shows a pot of hot rice which is covered with an airtight lid and left to cool. Why is it difficult to lift the lid when the rice is cold?

• Water vapour condenses on the lid

• The number of air molecules in the pot has decreased

• The adhesive force between the water molecules and the lid is strong

• The air pressure inside the pot is lower than the atmospheric pressure

Diagram shows a metal spoon immersed in a cup of hot tea. Thermal equilibrium is reached when

• Temperature of metal spoon = temperature of tea

• Mass of displaced tea = mass of metal spoon

• Volume of displaced tea = volume of metal spoon

• Specific heat capacity of tea = specific heat capacity of metal spoon

Answer explanation

The condition under which two substances in physical contact with each other exchange no heat energy. Two substances in thermal equilibrium are said to be at the same temperature..

Diagram shows a process of change of state. In which process, A, B, C or D, is latent heat of vaporization absorbed?

• A

• B

• C

• D

Answer explanation

The enthalpy of vaporization, also known as the heat of vaporization or heat of evaporation, is the amount of energy that must be added to a liquid substance to transform a quantity of that substance into a gas.

Specific heat capacity of water is 4200 Jkg^-1oC^-1. This means that 4200 J Heat energy is required to

• Change the temperature of 1 kg of water by 1 ^oC

• Change the temperature of 1 kg of ice by 1 ^oC

• Change 1 kg of water to steam at 100 ^oC

• Change 1 kg of ice into water at 0 ^oC

Diagram shows how a body temperature of a baby is measured by a doctor. The reading clinical thermometer is taken after a few minute to ensure...

• the net rate of heat flow is zero

• thermal equilibrium is not occur

• amount of heat transfer from baby to clinical thermometer and vice versa is not equal.

Calculate the time taken by a 800 W immersion heater to change 1 kg of ice at 0 ^oC to water at 60 ^oC.

(Specific heat capacity of water = 4200 Jkg^-1oC^-1, specific latent heat of fusion of ice = 3.4 x 10⁵ Jkg^-1)

• 315 s

• 425 s

• 740 s

• 1080 s

Which of the following graph shows the relationship between the volume and absolute temperature of a fixed mass of gas at constant pressure?

• 
• 
• 
• 

Diagram shows the cooling curve of naphthalene. At which stage the substance is in solid state and liquid simultaneously?

• MN

• NO

• OP

• MN and OP