The atomic mass of magnesium is the weighted average of the atomic masses of?

What is the overall order of reaction for rate = k[no]2[o2]

Astudent reacts 13 moles of iron with 21 moles of oxygen according to the following equation:

For the reaction c6h14(g) & longrightarrow; c6h6(g) + 4h2(g), δp(h2)/δt was found to be 2.5 x 10-2 atm/s, where δp(h2) is the change in pressure of hydrogen. determine δp(c6h14)/δt for this reaction at the same time.