(i) The surroundings become pleasantly warm when water in a lake starts freezing in cold countries.
(ii) The heat supplied to a substance during its change of state, does not cause any rise in its temperature.
Solution:
I Because ice’s specific latent heat of fusion is sufficiently high, a significant amount of heat must be released when the lake’s water freezes. As a result, the ambient temperature rises to a comfortable level.
(ii) To change the phase, only the latent heat of phase transition is necessary. As a result, the heat applied to a substance does not induce a temperature increase during its transition.