Use kinetic-molecular theory to describe what happens when an ice cube or icicle melts. Include how energy is involved and what happens to the motion of water molecules

The answer to your q the total mass is 73

The law of conservation of mass states that a mass of an object or the amount of matter composed inside an object or thing will not change unless it is added or removed of the matter that is contained in the object itself.

Moles = mass/molar mass the molar mass of c20 = 12.011*20 = 240.22 g per mole therefore, the number of moles is 20 g / 240.22 g per mol = 0.0833 moles.