Plzzzzzzzzzzzz send me its calculation with proper steps

find the average value of 1/r for 1s electron in hydrogen atom?

What do you mean by '1/r for 1s electron'?

Are you asking for the inverse of the radius of the 'orbit' of the 1s electron? :confused:

What you could do is use the formulae for circular motion and that for electromagnetic force.

F_c = \frac{mv^2}{r}

F_e = \frac{kq_1q_2}{r^2}

Equate both, substitute in values of m, the mass of the electron, q1 and q2, the charges on the nucleus and the electron, v, the velocity at which the electron travels and you can get 1/r.