Someone pls help me I WILL MARK BRAINLIEST

Solar energy is energy from the sun that is converted into thermal or energy. a. nuclear b. mechanical c. electrical d. chemical

2. how is heavy water different from normal water

What rule is used to determine how many covalent bonds an element can form? a. the number of covalent bonds is equal to six c the number of covalent bonds is equal to five minus the group number plus the group number b. the number of covalent bonds is equal to eight d. none of the above minus the group number select the best answer from the choices provided