State what is observed when iodine is heated in a test tube

Iodine is used for testing-

Some reduced iron filings and powdered roll sulphur are well mixed and heated in a test tube. Describe all what you observe.

Four test tubed marked I,II,III and IV were taken 20 ml of Al_2(SO_4)_3 solution in water was poured in each of the test tube I, an iron nails was put in test tube II, copper turnings were put in test tube III and a clean aluminium strip was placed in test tube IV. No change was observed in any four any in the test tubes. the correct inference drawn is

State your observations in the following cases : Ammonium chloride is heated in a hard glass test tube.

What happens when a solution of an acid is mixed with a solution of a base in a test tube?

Crystals of copper sulphate are heated in a test tube for some time. What is the source of liquid droplets seen on the inner upper side of the test tube during the heating process?