Question

hydrogen-2 is also known as deuterium as well as hydrogen-3 is known as tritium hydrogen-1 is our common hydrogen isotope a sample hydrogen gas has 99% hydrogen -1 ,0.8% deuterium , and 0.2% tritium what is the average atomic mass of this mixture of isotope to the thousands place

Answer 1

H-1 only has 1 proton and 1 electron, so its mass number is 1.
H-2 has one more neutron so its mass number is 2
H-3 has one more neutron than H-2 so its mass number will be 3.
average atomic mass = 1 x 99% + 2 x 0.8% + 3 x 0.2%
=1.012