Question

if you are given any liquid which cannot be tested how would you find out whether it is acid or a base

Answer 1

If the given liquid cannot be tested in any conventional method such as Litmus, or any other indicator, the best option would be to add another known acid or base to a sample of the liquid. If an acid is added to the liquid, then a reaction would indicate that the given liquid is basic in nature. Similarly, if an alkali is added to the liquid, then a reaction would indicate that the given liquid is acidic in nature.