Question

A watch glass containing some powdered substance is
placed between the pole pieces of a magnet. Deep concavity
is observed at the centre. The substance in the watch glass
is
(a) iron (b) chromium
(c) carbon (d) wood

Answer 1

The substance in the watch glass is iron. (Option a)

• According,to the data mentioned in the question,the material present in the watch glass shows concavity due to the presence of magnetic force.

• Now,this is only possible when the substance is a ferromagnetic substance.

• And,among the four substances mentioned in the question,only the iron has such ferromagnetic properties. (chromium can show ferromagnetic property in compound form, that's why chromium is omitted in this case.)

• So,the substance in the watch glass is iron.