What is the volume of 45.0 grams of nitrogen monoxide, NO, at 20
degrees C and a pressure of 740 mm Hg?

Hi!!

The molecular mass of the NO is (14g + 16g) = 30g and this is the
weight of one mol in grams. We have 45g of NO, then we have 45/30 =
1.5 moles of NO.

P = 740 mmHg = 0.973684 atmosphere    (760 mmHg = 1 atm)

T = (273 + 20)K = 293K

R = 0.082058 (L.atm/ K.mol)

According to the Ideal Gas Law:

V = n.R.T / P = 1.5 mol x 0.082058 (L.atm/ K.mol) x 293K / 0.973684
atm =
  = 37.04 L

I hope this helps. Please ask for a clarification if it needed before
rate this answer.

Regards.
livioflores-ga