Three nitrogen compounds and their formulae are listed: ammonia, $\text{NH}_3$; hydrazine, $\text{N}_2\text{H}_4$; hydroxylamine, $\text{NH}_2\text{OH}$. Which compound has the greatest relative molecular mass, $M_r$, and which compound has the largest percentage by mass of hydrogen?
- Ahighest $M_r$: $\text{N}_2\text{H}_4$; greatest percentage by mass of hydrogen: $\text{NH}_3$
- Bhighest $M_r$: $\text{N}_2\text{H}_4$; greatest percentage by mass of hydrogen: $\text{N}_2\text{H}_4$
- Chighest $M_r$: $\text{NH}_2\text{OH}$; greatest percentage by mass of hydrogen: $\text{NH}_3$
- Dhighest $M_r$: $\text{NH}_2\text{OH}$; greatest percentage by mass of hydrogen: $\text{N}_2\text{H}_4$