Question

how is that by connecting two spheres ,they become equipotential..?

Answer 1

you have to connect them by a conductor - then if there is a potential difference, charge will flow until the potentials are equal - which is what equipotential is...

Answer 2

a specific body can have a specific charge not more than that. so if extra charge is supplied it looses it. as they both hv been connected through a conductor or wire they both hold charge until their potential becomes equal bcause they cannot hv more than tht