Question

IF phosphorus is considered to contain $P_4$ molecules, then calculate the number of moles in 100 g of phosphorus.

Answer 1

As we know that the mass of one atom of phosphorous is 31 u
we know the mass of the molecule $=31\times 4=124u$
therefore 1 mole of $P_4$ = 124 gms
no of moles =$\frac{mass}{molarmass}$ $=\frac{100}{124}$ = 0.806 moles