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

Options

A. `1.993xx10^(-22)`mg
B. `1.993xx10^(-19)`mg
C. `4.983xx10^(-20)` mg
D. `4.983xx10^(-23)` mg

Answer

D

Explanation

Yellow phospharus is an impure form of white
phosphorus `(P_(4))`.
Molecular mass of yellow phosphorus `(P_(4))` ltbr. `=4xx 30 = 120 g mol^(-1)`
` therefore` According to Avogadro,s hypothesis,
Mass of `6.022 xx 10^(23)` molecules of `P_(4) = 120 ` g
and mass of 1 molecule of `P_(4) = (120xx1)/(6.022xx10^(23))`
`= 19.926xx 10 ^(-23)g`
`approx 1.993xx 10 ^(-22)g`
`= 1.993xx 10 ^(-19)` mg