Answer
The ratio of the mass of the hydrogen to the mass of helium is 3:1.
Work Step by Step
We are told that there are 7 times as many protons as there are neutrons. So, for every 2 neutrons, there are 14 protons.
A helium atom consists of 2 protons and 2 neutrons.
A hydrogen atom consists of 1 proton.
Two of the 14 protons combine with the 2 neutrons and make a helium atom of mass 4 u.
The remaining 12 protons make 12 hydrogen atoms, with total mass of 12 u.
There are 12 times as many H atoms as He atoms. Because H atoms have 1/4 the mass of He atoms, the ratio of the mass of the hydrogen to the mass of helium is 3:1. This was to be shown.
