What happens when some charge is placed on a soap bubble?

1. A

   Its radius increases

   (a) Its radius increases. Charge on a soap bubble adds electrostatic repulsion, lowering excess pressure; the bubble expands until a new equilibrium. That is the official key.

2. B

   Its radius decreases

   (b) Its radius decreases. Opposite of the electrostatic effect; surface tension alone would shrink, but added charge works against that.

3. C

   The bubble collapses

   (c) The bubble collapses. Charge does not pop the film as a first-order textbook result; radius grows.

4. D

   None of the above

   (d) None of the above. The radius-increase result exists, so ‘none’ fails.

Summary. Official key is (a) radius increases. A charged soap bubble expands because like charges repel and excess pressure falls. Honour the stored letter (a).