Question

In which things, NaHSO4 (Sodium Bisulfate) is found?

Answer 1

It is not found naturally but obtained in some of the reactions as by product.
NaHSO₄ is a by product in synthesis of HNO₃, it further reacts with sulphuric acid and forms Na₂SO₄ and HNO₃ is filtered from the solution.
It is acidic in nature hence used to lower the pH. It is an important chemical in toilet cleaner .