6. Give reasons for the following.
(a) There is a metal grill on the back of a fridge.
(b) Copper wires are commonly used in household cables.
(c) Graphite is used for making electrodes.
(d) Silver articles become black after some time when exposed to air.
Answers
A) Cooling coils at the back of refridgerators are made of copper because copper is a very good conducter of heat and electricity.A gas called freon22 flows through the tubes. This cools the refridgerator.
B) copper is often used in household wiring and cables, simply because it is a very good conductor of electricity and does not cost much compared to other conductive metals.
C) Graphite has some useful properties that make it desirable as an electrode in multiple applications, like electric arc steel production. The reasons being that graphite is cheap, plentiful, very stable over a broad range of operating conditions, scalable, durable/hard, and a good electrical conductor and heat conductor (a lot of heat is generated in electric arc steel production).
D)The silver article becomes black after sometimes when exposed to air because silver reacts with sulphur which is present in the atmosphere and then forms silver sulphide. Thus the layer of this silver sulphide is formed on the surface of the silver article so they appear as dull or black.
Hope this answer helps you good day.
Explanation:
(a) Because it is involved in recirculation refrigerant.
(b)Because it is a good conductor of electricity.
(c)Graphite is a good conductor of electricity. Also,it is cheaper.
(d)Because the silver articles reac