The chemical equation is given by :
[tex]Mg +2H_2O-> Mg(OH)_2+H_2[/tex]
From above equation :
24 gm Mg forms -----> 58 gm of [tex]Mg(OH)_2[/tex]
So, 11 g of Mg will form = [tex]\dfrac{11}{24}\times 58=26.58\ gm[/tex].
Now, percentage yield is given by :
[tex]\%\ yield = \dfrac{5.75}{26.58}\times 100\\\\\% \ yield = 21.63\%[/tex]
Therefore, the percentage yield is given by 21.63%.
Hence, this is the required solution.