Question

One atom of an elements $X$ weight $6.644\times {10}^{-23}g$. Calculate the number of gram atoms in $40Kg$ of it.

Answer 1

Weight of 1 atom $=6.644\times {10}^{-23}g$

1 gram atom = mass of 1 mole atoms $=6.023\times {10}^{23}\times \text{mass of 1 atom}$

$\therefore$ mass of 1 gram atom $=6.023\times {10}^{23}\times 6.644\times {10}^{-23}=39.99\approx 40g$

$\therefore$ no. of gram atoms in 40 gram of element X $=1$

$\Rightarrow$ no. of gram atoms in 40 kg of element X $=\frac{1}{40}\times (40\times {10}^3)=1000$

Hence, there are 1000 gram atoms in 40 Kg of element X.