Answer the following question: Fact 1: Boiling means change from a liquid into a gas by adding heat energy. Fact 2: Heat is Energy and is measured in Joules. Given the two facts above, boiling is changing from a liquid to a gas by adding what?

Choices:
i. Joules
ii. ice
iii. warmth
iv. air
v. water
vi. forces
vii. light
viii. digestion
Answer:
i.