Question

What is the mass of $6.02\times {10}^{23}$ atoms of calcium ?

Answer 1

In $1$ mol of $Ca$ there are $N_A$ individual calcium atoms.

$N_A$, Avogadro's Number $\cong 6.022\times {10}^{23}mo{l}^{-1}$.

The molar mass of $Ca$ is $40.08g\cdot mo{l}^{-1}$ which is one mole of calcium

$\therefore$ The mass $6.02\times {10}^{23}$ atoms of calcium is $40.08g$