What is the physical properties and the physical change ?

For ai it's atomic number is 13 and it's mass number is 27 how many neutrons does it have

The characteristic of two different types of reactions are shown below. reaction a: electrons are gained by the atoms of an element. reaction b: protons are lost by the atom of and element. which statement is true about the atoms of the elements that participate in the two reactions? a: their identity changes in both reaction a and b. b: their identity changes in reaction a but not b. c: their identity changes in reaction b but not a. d: their identity remains the same.

Describe at least two advantages and two disadvantages of using hydropower as a source of energy.