Question

One atom of an element X weighs 6.644 × 10^-23 g. Calculate the number of g-atom in 40 kg of it.

Answer 1

SOLUTION : We know that

gm-atomic wcight $=$ atomic weight in $gm =$ mass of $6.02 \times 10^{23}$ atoms

$\because \quad$ Mass of one atom $=6.644 \times 10^{-23} g$

$\therefore$ Mass of $6.02 \times 10^{23}$ atoms

$=6.644 \times 10^{-23} \times 6 \cdot 02 \times 10^{23} g$

$=40 \cdot 0 g =1 \cdot 0 g$-atom

no. of $g$-atoms in $40 kg =\frac{40,000}{40} g$-atoms $=1,000 g$ -atoms.