A charge q is placed at the centre of a sphere of radius r. The electric flux crossing the sphere is $\phi$. If both the charge and radius of the sphere are doubled, the electric flux crossing the sphere will be

$2\phi$

The correct answer is Option (2) → $2\phi$

By Gauss’s law:

$\phi = \frac{q}{\epsilon_0}$

Flux depends only on the enclosed charge, not on the radius of the sphere.

If charge is doubled ($q \to 2q$) and radius is doubled ($r \to 2r$),

New flux $\phi' = \frac{2q}{\epsilon_0} = 2\phi$

Answer: The new electric flux is $2\phi$