Number of atoms in 4.25 g of NH3is approximatly............
Molar mass NH3 = 14+3 = 17g/mol
given mass = 4.25g
no of moles = 4.25/17 = 0.25 mol of NH3
1 mol of NH3 contains 6.022*10^23 molecules
0.25 mol NH3 contains 0.25*6.022*10^23 = 1.5055*10^23 molecules
1 molecule of NH3 contains 4 atoms
Number of atoms in 1.5055*10^23 molecules = 4*1.5055*10^23 atoms.
The correct answer is = 6.022*10^23 atoms.