Ajay bought bottle that was labelled as distilled water. He suspected it to be tap water. What test he could use without adding any chemical in it to find out for sure?

Ajay should pass electric current through the water and connect a bulb to the circuit. If the bulb glows, it means that the water is tap water or else, it is distilled water.

Explanation:

This is because tap water contains little impurities like ions of some salts etc., which help in the conduction of electricity. But, distilled water is pure water and doesn't have any ions present in it. So, it doesn't conduct electricity.

Hope this helped