4) How does an atom have a charge of -3?

when it gains three electrons

Explanation:

In compounds an atom can have a charge of -3 after another atom gives it 3 more electrons (which are negatively charged) so even when it is gaining and you give it negatively charged atoms it will have a negative charge

conduction is the transfer of thermal energy (heat in transfer) due to collisions between the molecules in the object. collisions between adjacent atoms and molecules transfer kinetic energy from the warmer to the cooler object. the objects must be in physical contact.

the answer is minerals.