Question

​calculate the mass of one atom of calcium
​

Answer 1

$$\begin{gathered} 1moleofanyelementhasavogadronumberofatoms \\ 1moleofCa=Molarmass=40g \\ Thatmeans \\ 6.022\times {10}^{23}atomsofcalciumweigh40g. \\ 1atomweigh=\frac{40}{6.022\times {10}^{23}}\times 1=6.6423\times {10}^{-23}g \end{gathered}$$