Answer:
Stoichiometric Calculation:
3 NO₂(g) + H₂O (l) → 2 HNO₃(g) + NO(g)
2 moles of HNO₃ is produced from 3 moles of NO₂.
Therefore, By unitary method:
2.30 moles of HNO₃ produced from the moles of NO₂ = 
There are 6.022×1023 O2 molecules in a mole of O2. Since you have 2 oxygen atoms in one O2 molecule, there are 2×6.022×1023 O atoms in a mole of O2.
Check table T and use the concentration equation. Molarity= moles of solute/ liters of solution.
So 0.240 = x/ 1.65 once u find the # of miles of solute (x=.396) and substitute that
Wait I'm not sure if it's correct