Question

A student sets up an apparatus for determining the boiling point of water. He records
the temperature after regular intervals and finds that water when it begins to boil (1)
A. Remains constant
B. Continuously rises
C. First rises and then becomes constant
D. First remains constant and then rises

Answer 1

when the water begins to boil, the temperature first remains constant for the duration that water becomes vapour.  The heat supplied is used in converting water from liquid phase to gaseous phase.  the temperature remains at the boiling point - which is constant at the prevailing atmospheric pressure.