Fireworks exploding in the sky and giving off light are an example of a(n)

a. exothermic change
b. change in mass
c. physical change
d. endothermic change

Which of the following is a testable hypothesis? a. if i brush my teeth, i will get fewer cavities than if i don't brush my teeth. b. green toothpaste tastes better than blue toothpaste or red toothpaste. c. smart, careful, healthy people always brush their teeth. d. it's wrong to not brush your teeth before you have an important conversation with someone.

Which of the following statements about acidic water is true? a. acid has no effect on the h, o molecules. b. the solution contains a larger number of oh ions than h, o ions. c. the solution contains a larger number of h, o ions than qh ions. d. the solution contains an equal number of h, o ions and oh ions. none of the above e.

A50.0g sample of liquid water at 0.0 c ends up as ice at -20.0 c. how much energy is involved in this change?