(a) What are strategic metals? Give one example also.
(b) State the reason for the following behaviour of zinc metal:
On placing a piece of zinc metal in a solution of mercuric chloride, it acquires a shinsing silvery surface but when it is placed in a solution of magnesium sulphate, no change is observed.
(a) Strategic metals are generally defined as those metals which are required for the national defence of a country, but are threatened by supply disruption due to limited domestic production. Example; Chromium.
(b) Zn + HgCl2 → ZnCl2 + Hg
In the above reaction, Zn metal is highly reactive than mercury and can displace it from its salts solution easily. So, Silvery white colour is obtained due to formation of Hg, while in other case, happens due to less reactive nature of Zinc towards Mg.
Zn + MgCl2 = No reaction.