Question

What do you observe when:
(i) Iodine crystals are heated in a test tube?
(ii) Iron nails are added to copper sulphate solution?

Answer 1

(i) When Iodine crystals are heated, the van der Waals forces are easily overcome and the molecule breaks into the gas phase. They sublime and form a purple colored dense vapor.

(ii) When Iron nail (Ferrum) is dipped in Copper sulphate (${CuSO}_4$) there takes reaction between them and copper sulphate changes its color from blue to light green. This shows Iron is more reactive than Copper, it can replace Copper from ${CuSO}_4$.