7.52 X 10 25molecules of NH3

Explanation:

Find moles first

moles = number of particles/ 6×10^23

= 7.52 ×10^25 / 6×10^23

=125.33

calculate molar mass

(1×14) +(3×1) =17

convert to mass

mass= moles × molar mass

=125.33 × 17

=2130.67g

This is a pretty big value usually it's smaller but I'd assume it's because the number of particles was large.