Question

Find number of atoms of heliums. relative atomic mass of He is 4
1. 60amu sample
2. 20 g sample

Plz give step by step explanation.

Answer 1

1 mole contains 6.022×10^23 He atoms

1.60 g contains 60/4=15 moles

number of atoms,N=15×6.022×10^23

=9.033×10^24

2. 20/4=5 moles

N'=5×6.022×10^24

=3.011×10^24