Which elements were most abundant in the gaseous cloud that form the stars and planets of the solar system?

These planets were more massive than the inner planets and were able to attract large amounts of hydrogen and helium, which is why they are composed mainly of hydrogen and helium, the most abundant elements in the solar system, and in the universe.

a.   mass number from atomic number

force required to detach it is given by

charges are taken to be fundamental charge

now we have

so above is the minimum distance at which it will detach