Question

please answer A3....

Answer 1

After they have been touched, charge in both sphere is same or equal to,
$q=\frac{40-20}{2}=10$
as the distance remains same, the change in force is due to charge alone, the ratio of charge between initial and final configuration is

$\frac{(q_{1}q_{2})_{initial}}{(q_{1}q_{2})_{final}}= \frac{40*20}{10*10}=\frac{1}{8}$
so the answer is (A)