Question 55 of 126
A block of ice at is slowly heated and converted to steam at . Which of the following curves represent the phenomenon qualitatively:
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Answer: (D) 
When the state of the substance is not changing, temperature of the substance increases when heat is supplied to it. But when the substance changes the state, the heat supplied to it used as latent heat and the temperature remains constant until all the substance converts to other state.
Therefore, temperature of ice first increases from to . Then, remains constant at till whole ice is melted. Then, it increases from to . Again it remains constant at till whole water converts into steam.
Therefore, temperature of ice first increases from to . Then, remains constant at till whole ice is melted. Then, it increases from to . Again it remains constant at till whole water converts into steam.