A piece of ice at 0^o C is heated at a constant rate and its temperature recorded at regular intervals till steam is formed at 100^o C. Draw a temperature-time graph to represent the change in phase? Label the different parts of your graph. 

i) Name a gas caused by the Greenhouse effect.

i) Water in lakes and ponds do not freeze at once in cold countries. Give a reason in support for your answer.

ii) What is the principle of calorimetry?

iii) Name the law on which the principle is based.

Define the term ‘Heat Capacity’ and state its S.I. unit. 

What is meant by Global warming? 

i) It is observed that the temperature of the surroundings starts falling when the ice in a frozen lake starts melting. Give a reason for the observation.