Please help :)

1.
Mg + 2HCl → MgCl2 + H2
Is the equation above balanced? How do you know?

2.
Give an example of a substance changing temperature and what happens to the motion of molecules as the temperature changes?

1. Yes it’s balanced, because :
Left: 1 Mg - 2 H - 2 Cl
Right: 1 Mg - 2 H - 2 Cl

2. The molecules start moving faster when there is a higher temperature? The molecules also need more spce to move so the substance will expand. ex: glass breaks in really low temperatures because the molecules stop moving (not rlly sure about this answer, this fits more into physics :/)

The answer is d.potassium