What is the mass of one molecule of yellow phosphorus in milligrams ? (Atomic mass of P = 30)

Answer

`1.993 xx 10^(-19) mg`

Explanation

Molecular mass of yellow phosphorus `(P_(4))=30 xx 4 = 120g`
`6.022 xx 10^(23)` molecules of yellow phosphorus have mass `= 120 g = 120 xx 10^(3) mg`
1.0 molecule f yellow phosphorus has mass `= ((120xx10^(3)mg))/(6.022xx10^(23))=1.993xx10^(-23)mg`.