4. Heavier objects free-fall faster than lighter objects because of a. their greater mass
b. their greater air resistance
c. their greater weight
d. Nonsense! All objects free fall at the same rate.

The radiation of the fire causes the saucepan to heat up. the conduction of the saucepan then to distribute the heat over the saucepan and to give heat to the water. the convection of the water distributing the heat within the water, till all the water is boiling