Answer:

Explanation:
In all atoms, the number of protons = number of electrons, as a result the atom is neutral. Losing or gaining electrons will make the atom electrically charged and we call an electrically charged atom an ion.
Ca 2+ would be the symbol because losing two negative electrons makes calcium's nucleus more positive by two protons.
Hydroelectric power. That's just the term for electricity gained by using water, think of a water mill.
The velocity is 4374.45 m/s.
I got the answer by using v=d/t.
20,000meters / 25min= 4,374.45 m/s.
The answer is; C
In particular points in the earth’s surface, underground water is naturally heated to steam that can be harness for geothermal energy. The steam that ejects from the ground with high kinetic energy can be used to turn turbines that generate electricity. The underground water is usually heated by the hot rocks beneath that are subjected to the immense heat of magma or the enormous pressure of overlying crust.