Which of these is an element water oxygen sodium chloride or air

Nitrogen dioxide reacts with water to form nitric acid and nitrogen monoxide according to the equation: 3no2(g)+h2o(l)→2hno3(l)+no(g) part a suppose that 4.2 mol no2 and 0.50 mol h2o combine and react completely. which reactant is in excess? express your answer as a chemical formula. nothing

Which is the layer underground where all empty spaces are filled with a combination of air and water ?

Idon’t know how to solve this question