36 g of magnesium combines with 14 g of nitrogen. The simplest formula of the compound is:

1. Convert each mass to moles using the relative atomic masses, 24 for magnesium and 14 for nitrogen. 2. Magnesium: $\dfrac{36}{24}=1.5$ mol. Nitrogen: $\dfrac{14}{14}=1$ mol. 3. The ratio is $1.5:1$, which as whole numbers is $3:2$. 4. So the formula is $Mg_3N_2$. 5. This agrees with the valencies: magnesium is 2 and nitrogen is 3, and crossing them over gives the same result. _Source: NECTA CSEE 2021 Chemistry 032, Question 1: Multiple Choice, item (iv)_