Question

SECTION A
1.From the list given below, pick out the items which can be recycled:
Used clothes, polythene carry bags, glass bottles, newspaper

2.Alloys are used in electrical heating devices rather than pure metals. Give one reason.

3.A student has been collecting silver coins and copper coins. One day she observed a black
coating on silver coins and a green coating on copper coins. Which chemical phenomenon
is responsible for these coatings? Write the chemical name of black and green coatings.​

Answer 1

1.The items which are recycled are

used clothes, polythene carry bags, glass bottles, newspaper

2.Alloys are used in elecrtical heating devices because they thave high resistance and high melting point than pure metals.

3.The chemical phenomenon for which the silver coin turns black and the copper coin turns green is the corrosion(oxidation).The black coating of silver is silver sulphide and the green coating is copper carbonate.

Answer 2

The answer to the following question is as follows :

1. The items which can be recycled into a useable recycle product are newspaper and used clothes.

2. Alloys are used in electrical heating devices because they seem to indicate very high resistivity than any other pure metal and are termed to have a high melting point so significantly the electrical devices possessing high melting won't get burned at any kind of high temperature.

3.

(i) The chemical phenomenon which is responsible for the significant changes , i.e, black coating on silver coins and green coating on copper coins are termed as oxidation. So when metal surface comes in contact with the oxygen then it leads to the corrosion or oxidation of the metal.

(ii) Chemical name for the black coating is Silver Sulphide and for the green coating is Copper Carbonate.