Question

Calculate mass of 3g molecules of HNO_{​​​​3.}

Answer 1

gram molecule is same as mole

so you need to find out the mass of 3 moles of HNO3

molar mass of HNO3 = 1 + 14 + 48 = 63 g or more precisely it is 63.0128 grams

3 moles = 3 x 63 g = 189 grams. That would be the mass.

Hope it helps