Hello,
As you have not specified for which college or which class,course,stream or branch you want the science answer key for it is a bit difficult to answer the question.
But I recommend you to search on google for whichever science papers that you want as there are many private sites on net which provide various answer keys.Please provide the information in detail below.
Hope this helps.
Regular exam updates, QnA, Predictors, College Applications & E-books now on your Mobile