Question

The process of giving a coating of_____ to copper or brass is called tinning.
A.Zinc
B.Copper
D.Tin
E.Iron

Answer 1

Copper is a ductile metal while Brass is an alloy of zinc and copper. Copper and brass are used to make cooking wares and vessels as they are both good conductors of heat and electricity. Copper or brass corrode when left unprotected in the air just like iron.

Complete Step-by-Step Solution:
Copper or brass if left out in the air undergoes oxidation with oxygen and forms a greenish coating due to corrosion. This greenish substance is copper carbonate. The reaction is given as-
${\text{2Cu + }}{{\text{H}}_{\text{2}}}{\text{O + C}}{{\text{O}}_{\text{2}}}{\text{ + }}{{\text{O}}_{\text{2}}} \to {\text{Cu}}{\left( {{\text{OH}}} \right)_2} + {\text{CuC}}{{\text{O}}_{\text{3}}}$
This substance is poisonous. We know that copper and brass are used to make cooking utensils so if milk or any other substance is placed in the corroded utensil, it also becomes poisoned.
So tin is used to coat the surface of copper or brass so that corrosion can be prevented. This process is called tinning.
a)Tin is also used to coat wrought iron or steel to prevent rusting. The produced product is known as tinplate.
b)Tin is also used as a non-toxic exterior in medical implants such as prostheses.

Answer- Hence the correct answer is C.

Note: The uses of brass are-
a)It is used to make doorknobs and other bathroom materials due to its antimicrobial properties as bacteria cannot grow on its surface.
b)It is used to make musical instruments and decorative items.
c)It is also used in firearm cartridge casing and radiators.
d)It is used to make pipes.