Question

When two hydrogen atoms approach each other to form a chemical bond,?

Answer 1

When two hydrogen atoms approach each other to form a chemical bond, both attractive and repulsive forces are present. This is due to the negative and positive charges within the atoms. The electrons of each of the hydrogen atoms repel each other, while the nuclei also repel each other. At the same time, the electron and nucleus of both hydrogen atoms attract each other. So the answers are:

2. when to atoms of H approach each other,the two nuclei repel each other
3. when to atoms of H approach each other, each electron is attracted by the other nucleus 

Answer 2

During formation of H2 molecule two hydrogen atoms approach each other

in general

a) opposite charges attract each other

b) similar charges repel each other

c) electrons are negatively charged

d) nucleus is positively charged due to presence of protons

thus we can say that

When two hydrogen atoms approach each other

a) the two nuclei (positively charged) repel each other

b) each electron (negatively charged) is attracted by other nucleus.