Question

when hydrogen burns, it reacts with oxygen in the air. what product is formed from this reaction?
water (h2o)
carbon monoxide (co)

Explanation:

The reaction of hydrogen ($\ce{H_2}$) burning in oxygen ($\ce{O_2}$) is a combustion reaction. The chemical equation for this reaction is $\ce{2H_2 + O_2\xlongequal{点燃} 2H_2O}$, which produces water. Carbon monoxide (CO) requires carbon - containing reactants, and since the reactants here are only hydrogen and oxygen, CO cannot be formed.

Answer:

A. water ($\ce{H_2O}$)