The same compound has density 0.977 g/L at 710 mmHg and 100°C, giving $M_r\approx32$. Its molecular formula is:

1. Find $M_r$ from the gas density using $M_r=\dfrac{\rho RT}{P}$. 2. With $\rho=0.977$ g/L, $T=373$ K and $P=\dfrac{710}{760}=0.934$ atm, this gives $M_r\approx32$. 3. The empirical formula NH₂ has a mass of $14+2=16$. 4. So $n=\dfrac{32}{16}=2$. 5. Multiplying the empirical formula by 2 gives N₂H₄, hydrazine. Reporting NH₂ stops at the empirical formula and ignores the density data. _Source: NECTA ACSEE 2023 Chemistry 132/1, Question 1: Gases_