4. Heat required for boiling water is known as: a) heat of formation. b) heat of vapourization. c) heat of fusion. d) heat of solution.

Option B

Explanation:

The best answer to this question is option B "heat of vaporization." When you add heat to a pot of water and the water starts to boil the water starts boiling/vaporizing into a gas called water vapor. The heat transformation is also known as the heat of evaporation where it's the amount of energy required to heat a pot of water to it's boiling point where it starts evaporating.

Hope this helps.

yes the answer is total mass in unchanged   : )