2 charged metal spheres of radii R and 2R teemporarily placed in contact and then seperated.At the surface of each which sphere has the greater value of tha following:a.charge b.charge density c.potential d.electric field

As the two spheres were kept in contact earlier, the potential on the surfaces of the two would be same, even after separation. 

So, by using the above we can deduce that

V (bigger sphere) = V' (smaller sphere)

or

kq/R = kq'/r

now, as R> r, we get

the charges

q > q'

so, charge density

σ < σ'

and finally

as E = kq/R²  and  E' =  kq'/r²

so,

E > E'

(a) charge on bigger sphere is greater

(b) charge density of smaller sphere is greater

(c) potential is same for both

(d) electric field is greater for the bigger sphere