Answer 1:
Correct Answer: Option A i.e. The temperature stays constant for a while, then rises (A).
Reason:
At 0 oC, H2O exist in dual state (solid and liquid) i.e. there exist an equilibrium between ice and water. Hence, when the heat is supplied, it is initially used to bring about phase transformation from solid to liquid state. During this time, temperature remains constant. Once the phase transformation has occurred, heat is utilized for increasing the temperature of system i.e. water.
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Answer 2:
Correct Answer: Option B) At first, the energy supplied goes into overcoming attractive forces in the solid.
Reason:
In the present case, initially the energy supplied goes into overcoming attractive forces in the solid. Once the ice is converted into water, it now exist in single phase i.e .liquid. Hence, now when further heat is supplied to the system, it is used only for increasing the temperature of system.