Question

WHY DOES A DENSE WHITE DEPOSIT APPEAR NEAR THE TOP OF TUBE IN WHICH AMMONIUM CHLORIDE IS HEATED

Answer 1

Explanation:

when ammonium chloride is heated it changes its state from solid to gas (which is known as sublimation). When the gas comes in contat with the cooler part of test tube,its temperature lowers down and it then chages its state from gas to solid ,this is what we see as white precipitate on the upper part of test tube.