Atoms Rearranged in Reactions Practice Test

A particle model shows water decomposing: $2\text{H}_2\text{O} \rightarrow 2\text{H}_2 + \text{O}_2$. Which set of bonds breaks and which set of bonds forms?

A particle model shows ammonia forming: $\text{N}_2 + 3\text{H}_2 \rightarrow 2\text{NH}_3$. Before: one N≡N molecule and three H–H molecules. After: two molecules where each N is bonded to three H atoms. How many hydrogen atoms are present before the reaction, and how many are present after the reaction?