If you wanna do Science in the Uni, you should be aware that H1
level is useless for use as prerequisites.
Almost all Science courses in the Uni require either H2 Chem or H2
Physics, in addition to H2 Maths. You *must* take these subjects at
H2 levels.
It is always safest to take Econs as your H1, since Econs at A
levels is not required at all, even if you wanna study Econs in the
Uni.