$1.2\mathrm{g}$ of $\mathrm{Mg}$ (At Mass 24) will produce $\mathrm{MgO}$ equal to?

Step 1: Given data:

The amount of $\mathrm{Mg}$(At Mass 24) =$1.2\mathrm{g}$

Step 2: Formula used :

The formula to calculate the number of moles of a substance is :

$No.ofmoles=\frac{Givenmass}{Molarmass}$

Step 3: Writing the balanced equation for the reaction:

The balanced equation for the reaction is: $\mathrm{Mg}+{\mathrm{O}}_2\to \mathrm{MgO}+\frac{1}{2}{\mathrm{O}}_2$

Hence, it is clear from the reaction that $1\mathrm{mol}$of $\mathrm{Mg}$ reacts to give $1\mathrm{mol}$ of $\mathrm{MgO}$.

Step 4: Calculation of the number of moles:

Calculating the number of moles of $\mathrm{Mg}$ using the formula:

$No.ofmolesofMg=\frac{1.2}{24}=0.05$

Since, $No.ofmolesofMg=No.ofmolesofMgO=0.05$

Thus,$1.2\mathrm{g}$ of $\mathrm{Mg}$ will produce$0.05$ moles $\mathrm{MgO}$.