Question

a sample of nitrogen contains 90%N14 and 10 %N15 isotopes.the average number of neutrons per atom is

Answer 1

Nucleus = nutron +proton

N¹⁴ n+p=14 ;n=7

N¹⁵ n+p=15 ; n=8

90% of N¹⁴= (7*90)/100
10% of N¹⁵⁼ (8*10)/100
Number atom =2(given)

average number of neutrons per atoms = total number of neutrons/number of atom in sample
= (7*90/100+8*10/100)/2
=3.55


*n=neutron ; *p=proton