Correct Answer:
(D)
Copper
Copper is a metal, however steel, brass and bronze are alloys.
Ques:
2
Consider the following statements:
Assertion (A) : Galvanized iron does not rust.
Reason (R) : Zinc has the efficiency of oxidation.
Code :
(a) Both
(A) and (R) is correct, and (R) is correct explanation of
(A).
(b) Both
(A) and (R) is correct, but (R) is not the correct explanation of
(A).
Correct Answer:
(A)
Galvanization is the process of applying a protective zinc coating on steel or iron to prevent them from rusting and oxidation. The zinc forms a barrier between atmospheric oxygen and the underlying iron or steel. It does this by transferring electrons and oxidizing more quickly than iron. This rapid zinc oxidation prevents ferrous metals from rusting until the zinc has exhausted its free-electron capacity or the protective coating has worn away.
Ques:
3
Which one of the following is essential in corrosion of iron metal?
Correct Answer:
(B)
Oxygen and moisture
Oxygen and moisture are essential in corrosion of iron metal. Iron corrosion is generally characterized by the formation of rust due to an electrochemical process in the presence of oxygen and moisture (water) in the surrounding environment. When iron reacts with water and oxygen, iron (II) hydroxide is formed. The latter further reacts with oxygen and water to form hydrated iron (III) oxide-widely known as rust.
Ques:
4
Which metal is generally used for coating of brass utensils to prevent copper contamination?
Correct Answer:
(A)
Tin
The coating of tin on brass utensils prevents copper contamination. Tin is a soft and white metal like silver. Its symbol is Sn with atomic no. 50.
Ques:
5
Aluminium surface is often 'Anodized'. This means the deposition of a layer of –
Correct Answer:
(B)
Aluminium Oxide
Anodizing is an electrochemical process by which the surface of a metal is made durable and rust resistant. In this process, a layer of aluminium oxide is deposited on aluminium.
Ques:
6
Alloy of which metal is used to make aeroplane and parts of the compartment of the train?
Correct Answer:
(C)
Aluminium
Low density and strength make aluminium ideal for construction of aircraft, lightweight vehicles and ladders. An alloy of aluminium called Duralumin is often used instead of pure aluminium because of its improved properties. Easy shaping and corrosion resistance make aluminium a good material for drinking cans and roofing materials.
Ques:
7
Mercury-metal mixture is –
Correct Answer:
(C)
Mercury mixed alloy
An amalgam is a substance formed by the reaction of Mercury with another metal. Almost all metals can form amalgams with Mercury, the notable exception being Iron.
Ques:
8
Solder used in soldering metal pieces is an alloy of :
Correct Answer:
(A)
Tin and Lead
The common composition of solder is 32% Tin, 68% Lead. This combination has a low melting point and is useful for soldering components that are sensitive to heat.
Ques:
9
Bronze is an alloy of –
Correct Answer:
(A)
Copper and Tin
Bronze is an alloy made up of Copper and another metal Tin. Compositions may vary but most modern bronze is 88% Copper and 12% Tin.
Ques:
10
Match List-I with List-II and select the correct answer using the codes given below the lists :
List-I List-II
A. German silver 1. Tin
B. Solder 2. Nickel
C. Bleaching powder 3. Sodium
D. Hypo 4. Chlorine
Code :
A B C D
Correct Answer:
(D)
2 1 4 3
German Silver or Nickel silver is an alloy consisting 50% Copper, 35% Zinc and 15% Nickel. It doesn't have Silver. Solder of Tin and Lead is known as soft solder. The chemical name of bleaching powder is calcium hypochlorite Ca(ClO)2. Sodium Thiosulphate (Hypo) is a crystalline white smell-less solid.