1. is D. Scientific method cannot be replaced.
2. is B.
3. is B as well.
They are halogen elements, or nonmetallic elements in the same GROUP, specifically group 17
The amount of heat needed to increase the temperature of a substance by

is given by

where
m is the mass of the substance

the specific heat capacity

the increase in temperature
In our problem, the mass of the water is m=750 g, the specific heat is

and the amount of heat supplied is

, so if we re-arrange the previous formula we find the increase in temperature of the water: