Question

What natural barrier tries to prevent two protons from combining?

Answer 1

The Coulomb barrier prevents two protons from combining.

Explanation:

As protons are positively charged and like charges repel. The unit of charge is called the coulomb. So, the proton charges tend to keep them apart.

In the centre of a star where temperatures and pressures are high enough, protons can be bought close enough for the strong nuclear force to bind them into the highly unstable helium 2 `""_2^2He`. Most of these nucleii decay back into two protons, but if the weak nuclear force comes into play one proton will decay into a neutron and a positron to create a stable deuterium nucleus `""_1^2H`.