Q.8 Match the substances given in Column A with their uses given in Column B.
A
(i) Gold
(ii) Iron
(iii) Aluminium
(iv) Carbon
(v) Copper
(vi) Mercury
B
(a) Thermometers
(b) Electric wire
(c) Wrapping food
(d) Jewellery
(e) Machinery
(f) Fuel

A

(i) Gold
(ii) Iron
(iii) Aluminium
(iv) Carbon
(v) Copper
(vi) Mercury

B

(d) Jewellery
(e) Machinery
(c) Wrapping food
(f) Fuel
(b) Electric wire
(a) Thermometers

EXPLANATION :

1) Gold does not tarnish, rust or corrode upon their usage in daily life. Due to its wonderful properties and its luster, gold is considered as the most important metal in jewellery making.

2) Iron is used to make machines because they are hard, strong and do not show wear and tear so easily. There are many applications of gray iron which include automotive engine blocks, gears, flywheels, brake discs & drums and machine bases. Gray iron serves well in machinery applications because exhibits good fatigue resistance.

3) Aluminium is used for wrapping food items because it is flexible and non-reactive with the food ingredients. Aluminum is a soft and malleable metal. It can be easily beaten into thin sheets to form wrapping foils.

4) Carbon is used as fuel because they burn with a clean flame and thus no smoke is produced. Carbon and their compounds give out a lot of heat, energy and light when they are burnt in air and this is mainly because carbon compounds have greater calorific values.

5) Copper is used to make electric wires because it has low resistivity towards electrical current and thus consumes less power. Hence it is as an excellent conductor of electricity. Copper is also less oxidative than other metals.

6) Mercury is used as liquid in thermometers because it is the only metal that exists in liquid state at room temperature. It has high coefficient of expansion, so that it can note even the slightest change in temperature.