Please give the answer properly. The maximum charge that can be given to the given sphere

If the sphere is isolated metallic sphere, then field at it's surface is given by

E=kQ/R^2……………..(1)

Here,k=(1/4Pi eo)=9x10^9 Nm^2C^-2

eo is permittivity of space.

Q is charge given to the sphere. In case of metallic sphere this charge resides on the surface of the sphere.

The field produced by this sphere at the surface and outside, can be obtained by using spherical Gaussian surface. This field is such that as if entire charge Q is situated at the center of the sphere leading to equation (1).

E=3x10^6 V/m (given)

Now,from (1),

Q=ER^2/k= 3x10^6x25/(9x10^9) C=(25/3)(10^-3)C