Question

Calculate the amount of magnesium oxide (in g) in products.

• A. $28$
• B. $20$
• C. $16.8$
• D. $32$

Answer 1

The correct option is A $28$

$3$ moles of magnesium gives $2$ moles of ammonia.

Thus, $3.4$ g of ammonia will be formed by $\frac{3\times 24\times 3.4}{34}=7.2$ g of magnesium.

The amount of magnesium that reacts with oxygen to form $MgO$ is $24-7.2=16.8$ g.

The amount of $MgO$ formed is $\frac{16.8\times 40}{24}=28g$.