What happens to the number of valence electrons as you move up a group

How does a hydroelectric power plant converts energy into energy.

Which answer tells the reason the earth’s climate is getting warmer? too many animals are becoming extinct. large glaciers are melting in antarctica. the earth is moving closer to the sun. driving cars gives off gases that trap heat in the atmosphere.

If many scientists conduct the same or similar experiments, and all obtain similar results, a can be written, which is a generally agreed-upon statement that explains and predicts how a natural phenomenon works.