When the distance between charged parallel plates of a capacitor is d, the capacitance is c.

if the distance is increased to 2d, how will the capacitance change, if at all?

Capacitance will be decreases to

Explanation:

We have given that capacitance between the plates is C when the distance between the plates is d

We know that capacitance between the plates is given by

, here d is the distance between the plates

From the relation we can see that capacitance is inversely proportional to distance

So if we increase the distance to 2d then capacitance will be decrease to  

like poles repel so keep pushing north to north and repels funny to see this