Which organelle converts the chemical energy stored in food into compounds that are more convenient for the cell to use?

The mitochondria does that

Aneutral atom must have the same number of neutrons and protons? no, they must have the same number of protons and electrons

Iwould say overuse ( but not 100% sure ) in the u.s. we tend to overuse water by leaving it running, throwing it away, taking long showers, etc.