Question

calculate the mass of NH3 in 7.5 mole

Answer 1

mass of N IS 14
MASS OF H3 IS 3
total mass is 17 for 1 mole
then u have to multiply 17
$17 \times 7.5 = 127.5$

Answer 2

Mass of 1 mole of Nitrogen=14g
Mass of 1 mole of hydrogen=1g
hence molecular mass of 1 mole of NH3 is 14+ 1*3=17g
therefore molecular mass of 7.5 moles of NH3 is 17 * 7.5 = 127.5 g