The length of scientific papers is very different, therefore an ideal word count cannot be defined. It depends on what has to be reported. But check the instructions for authors before submitting a paper to a journal whether there is an upper limit of the length.
Hi Sangeetha, first and most importantly your paper must meet the requirements of the journal in terms of their word limit. Second, journals ,will have a word 'limit', and this should not be confused with a word 'target'. Write as much as you need, and not a word more.