Answer : 2.69 $\times$ 10$^{16}$

$PV = nRT \rightarrow n = \large\frac{PV}{RT}$

Number of particles $ = nN_A =\large\frac{PV}{RT}$$N_A = \large\frac{1 \times 1.013 \times 10^5 \times 1 \times 10^{-9} \times 6.02 \times 10^{23}}{8.315 \times 273}$$ = 2.69\times 10^{16}$