Question

A watch glass containing some powdered substance
is placed between the pole pieces of a magnet. A
deep concavity is observed at the centre, which
implies that the substance in the watch glass is
(1) iron
(2) chromium
(3) carbon
(4) wood​

Answer 1

Answer:

Your answer is Iron

Explanation:

The substance in the watch glass is iron since it is ferromagnetic material (with positive charge on it) hence when kept in between two pole pieces it will attracted by negative one and repelled by positive one and deep concavity is observed at the center.

Hope it helps......