The correct answer is (c) (ii) and (iii).
Explanation:
(ii) Some hydrogen gas leaking out of the container:
When gas leaks out, the number of molecules decreases in the same volume, which means the molecules have more space to spread out, increasing the distance between them.
(iii) Increasing the volume of the container of hydrogen gas:
If you expand the container while keeping the same amount of gas, the molecules will have more space to occupy, leading to a larger distance between them.
Why other options are incorrect:
(i) Increasing pressure on hydrogen contained in a closed container:
Increasing pressure means more gas molecules are forced into the same space, which actually decreases the distance between them.
(iv) Adding more hydrogen gas to the container without increasing the volume:
If you add more gas without changing the container size, the molecules will be closer together due to the increased number of molecules competing for the same space.