Question

Magnesium and oxygen combine in the ratio of $3:2$ by mass to form magnesium oxide. What mass of oxygen gas would be required to react completely with $24g$ of magnesium?

Answer 1

$Mg9+O\to MgO$

Let mass of $Mg$ be $3x$

then mass of $O$ be $2x$

no. of moles in $24$ kg of $Mg=\frac{24}{24}=1mole$

as $1mole$ of Mg react with $1$ mole of $O$

So, $1$ mole of $O$ is required ti react completely with $24$ g of $Mg$

$1$ mole of $O$ has $16$ g mass

Thus $16$ g of $O$ is required to read completely with $24$ of $Mg$.