Question

What is the number of atoms in 8.5 g of NH3?

Answer 1

the molar mass of NH3 is equals to 17 gram.
Moles of NH3 in 8.5 gm =8.5/17=0.5
thus molecules in half mole NH3 is 6.022×10^23×0.5

and atoms in half mole NH3=0.5× 6.022×10^23×4
now calculate it

Answer 2

Answer: $12.05\times 10^{23}$

Explanation: According to Avogadro's law, 1 mole of every substance contains avogadro's number of particles $(6.023\times 10^{23})$ and weigh equal to the molecular mass.

Molecular mass of $NH_3$ = 17 g

17 g of $NH_3$ contains=$(6.023\times 10^{23}$ molecules of $NH_3$

1 molecule of $NH_3$ contains= 4 atoms

17 g of $NH_3$ contains=$4\times 6.023\times 10^{23}=24.1\times 10^{23}$ atoms

8.5 g of $NH_3$ contains=$\frac{24.1\times 10^{23}}{17}\times 8.5=12.05\times 10^{23}$ atoms.