How many moles of 02 are consumed when 0.770 mol of magnesium burns in excess oxygen?

 0.385 moles

Explanation:-

Combustion is a type of chemical reaction in which a substance is reacted with oxygen.

The balanced chemical reaction between magnesium and oxygen is:

From the stoichiometry:

2 moles of magnesium react with = 1 mole of oxygen

Thus 0.770 moles of magnesium react with = moles of oxygen

Thus 0.385 moles of are consumed when 0.770 mol of magnesium burns in excess oxygen.

it is b that is the answer.