If most objects are made up of free space then why can we put our hands through a book or wall?

I suppose you mean to ask why we can't go through obstacles.

Any atom is surrounded by an electronic cloud. When two atoms get close to each other, the electronic clouds repel each other, preventing them from interpenetrating each other. That same phenomenon, on a larger scale, prevents us from going through matter.

Idon't know hope someone you

Ithink the answer is d