Question

Calculate the number of molecules in $35.5g$ of chlorine gas.

Answer 1

Since 35.5g is one mole of chlorine, we have $6.022\times 10^{23}$ molecules of the gas.

Since chlorine gas is diatomic ($C{l}_2$), there are $2\times$$6.022\times 10^{23}$=$1.204\times 10^{24}$ atoms of chlorine in the 1 mole.