Do i need to have all the subjects i take in alevel in one cetificate to apply to recognised universities. I am planning to take my chemistry and biology exams 2019 may and physics and psycology in 2019 October that won't have a issue when applying to universities in uk?
They don't necessarily need to all be on one certificate (indeed students in the UK often sit A-levels from different exam boards and thus have them on different certificates anyway), but you will need the proof of them in some form as above.
However, some universities and courses prefer you take at least three A-level exams (and normally, all of them that you are entering for) in a single sitting, to ensure you are prepared for their courses and so they can compare you equally with other students who have done the same. Especially for e.g. Oxbridge, Imperial, LSE, and medicine, dentistry, vet met, and similar courses, it's normally expected you will take all your equivalent exams together (e.g. all A2 exams at the same time - taking your AS exams before those is fine).
Is there a reason you're only doing them in two sets of two? I would recommend you check the requirements of any courses or universities you are hoping to apply to in order to ensure this approach would be acceptable (it may be worth contacting the universities directly to enquire).
As said, many unis ask or prefer to take all exams in one sitting.