PLEASE HELP!
Isla made ice by putting water in the freezer. Freezing is an example of (2 points)
a chemical change
a nuclear change
a physical change
an atomic change

The diagram shows a boulder rolling down a hill into a valley and then up the opposite hill. at which position does the boulder have the greatest kinetic energy? a b c d

What electron configurations do atoms usually achieve by sharing electrons to form covalent bonds?

Hydroelectricity provides about 7 percent of the electricity generated in the united states. (a) explain how a hydroelectric power plant converts energy stored in water into electricity. (b) identify two factors that determine the amount of electricity that can be generated by an individual hydroelectricity power plant. (c) describe the two main types of land-based hydroelectric power plants. (d) describe two economic advantages and two environmental disadvantages of hydroelectricity.