Answer:
2. +0.2 C
Explanation:
When the two spheres touch, the total charge will be redistributed such that the two spheres are at same potential:
The potential can be rewritten as ratio between the charge on the sphere (Q) and the capacitance of the sphere (C):
Since the two spheres are identical, they have same capacitance:
So we can write
And since the total charge is
And this charge will be redistributed equally on the two spheres (), we have