hello

If we talk about chemistry and computer science, as individual subjects, both are quite heavy. I would suggest go for computer science since there will be less theory to mug up and computer is also an ever-green subject and now a days, every recruiter want his employee to be able to operate computers. Computer science will have more concepts that you'll need to just understand as its a application based subject.

If you are very good at learning theory than only go for chemistry.

Hope this helps you

All the best!