Question

calculate the no.of atoms in 0.008g of phosphorus

Answer 1

as we know moles = given mass / molar mass

and given mass = 0.008g

and molar mass of phosphorus is 31 so

moles = 0.008 / 31 = 0.000258 = 2.58 * 10^-4

and as we know no of atoms is = moles * avagadro no ( 6.022 * 10 ^ 23)

so no of atoms = 2.58*10-4 * 6.022*10 ^23

= 15.8 * 10 ^19

and * means sign of multiply

Answer 2

n=given mass/molecular mass

n=0.008/30

n=2.6*10^-4