What is the checmical symbol for Thorium^+2?

I'm confused with ^+2

Achange in the number of neutrons in an atom will change an blank . when the number of protons changes in an atom, a new element will form.

Identify the electromagnets with poles that are reversed from the electromagnet shown above

Consider this equilibrium: n29) + o2(g) + 2no(c).nitrogen gas and oxygen gas react when placed in a closed container. as the reaction proceeds towards equilibrium, what happens to the rate of thereverse reaction?