Question

Give reasons:
a. Why is pure gold not suitable for making ornaments?
b. Why is calcium found in the form of compounds?
c. Why are electrical wires coated with PVC (Poly Vinyl Chloride)?
d. Why do we apply oil on iron tools kept in storage?
e. Why is sodium stored in kerosene oil?

Answer 1

Hint: - For these types of questions we must understand the property of substance and also their reaction properties.

Complete answer:
a. Why is pure gold not suitable for making ornaments?
Ornaments that are made from 24-carat gold which is pure gold are very rare since pure gold is very soft and is prone to wear and tear upon usage. Therefore, 22-carat gold is generally used which contains a slight amount of copper, silver and other metals in order to improve wear resistance and at the same time it also retains its elegance.

b. Why is calcium found in the form of compounds?
Calcium is a metallic element that is very reactive with water and other substances. Due to its high reactivity, calcium tends to react with oxygen and water and other elements to form compounds. As we know, both water and oxygen are also easily available in our environment that's why the chances of chemical reaction of calcium with other easily available substances is pretty high. And for this reason, the actual availability of the calcium in the environment is more in the form of a chemical compound.

c. Why are electrical wires coated with PVC (Polyvinyl Chloride)?
PVC is a short form of Polyvinyl Chloride. It is a polymer which is an insulator which means it does not allow electricity to pass through it. Also, if by any chance anyone touches the wire while the switch is on, one will not get electric shock as PVC acts as a barrier.

d. Why do we apply oil on iron tools kept in storage?
Iron is reactive in nature. It can react with moisture and oxygen present in the atmosphere to form oxide or undergo corrosion which is called rusting. So, to prevent rusting of iron we apply oil. As we know oil prevents iron from the atmosphere and hence iron tools are safe during storage.

e. Why is sodium stored in kerosene oil?
Sodium is a highly reactive metal and reacts vigorously with the oxygen, carbon dioxide and moisture present in the air. Due to this vigorous reaction they may even cause fire. To prevent this reaction, sodium is kept immersed in kerosene because Sodium doesn't react with kerosene.

Note: - While solving these types of questions the property of elements and their periodicity plays a very important role. Also, the property of an element to react with other things like water, oxygen, carbon dioxide etc. also plays a very important role.