The expected answers are:

(a)Boiling point of a liquid is defined as the temperature at which the saturated vapour pressure of the liquid is equal to the (external) atmospheric pressure

Diagram correctly showing and labelling the components as shown above. Score zero if any component(s) except stirrer is missing.

Description

-A few drops of liquid are trapped in the closed limb of the J-tube above the mercury
-The J -tube, thermometer and stirrer are inserted into a beaker of water
-The beaker and content is heated while stirring continuously
-The temperature of water is read and recorded when the mercury levels in the two limbs are the same.
-The beaker is heated a little further before heat source is removed
-A second temperature is read and recorded when the mercury levels are once again the same.
-The mean of the two temperature values is the boiling point of the liquid.

Heat lost by copper = Heat gained by water
        0.3 x 400 x (950 - 100) = 0.25 x 4200 x (100 - 25) + 2.26 x 106 m
        0.3 x 400 x 850 = 0.25 x 4200 x 75 + 2.26 x 106 m
        102000 = 78750 + 2.26 x 106 m
            m = 102000 - 78750
                        2.26 x 106

        = 0.0102876kg = 10.3g

This question on heat energy was quite popular. It was also fairly well attempted by many candidates.
In part (a), most candidates were able to correctly define boiling point.
In part (b), the description of the experiment to determine the boiling point of a small amount of liquid with the aid of a diagram recorded a lot of weaknesses. These include
(i)inability to draw a complete diagram or to correctly identify the components of the set up;
(ii)inability to present a clear sequential description of the experiment;
(iii)inability to identify the content of the J- tube.

Some few candidates also filled up the J-tube with the liquid thereby leaving no space for vapour.
The calorimetry numerical in part (c) was quite satisfactorily handled by many of the candidates.