A quantity of 12 g of magnesium is burnt completely in air ( ${\text{O}}_{\text{2}}{\text{= 20\% and N}}_{\text{2}}\text{= 80\%}$ , by volume). Which of the following is/are correct statements regarding this combustion?

$\text{MgO}$  and  ${\text{Mg}}_{\text{3}}{\text{N}}_{\text{2}}$  are formed 
$$\begin{gathered} {\text{2Mg + O}}_{\text{2}}\to \text{ 2MgO} \\ {\text{3Mg + N}}_{\text{2 }}\to {\text{Mg}}_{\text{3}}{\text{N}}_{\text{2}} \\ {\text{14Mg + O}}_{\text{2}}{\text{+ 4N}}_{\text{2}}\to {\text{2MgO+ 4Mg}}_{\text{3}}{\text{N}}_{\text{2}} \end{gathered}$$
Number of moles of Mg = 0.5 moles,  ${\text{O}}_{\text{2}}$ and  ${\text{N}}_{\text{2}}$ in the air will be in 1:3.5 mass ratio in the.
Wt of  $\text{MgO}$  if it is only formed is 20g and O₂ consumed is 8g and the total air requires is 8+28 = 36g
Wt of  ${\text{Mg}}_{\text{3}}{\text{N}}_{\text{2}}$  if it is only formed = 16.666g and N₂ consumed is 4.666g
One mole of Mg give 34.28g of product (mixture of oxide and nitride) so Half mole gives 17.14g