Corrosion

Q.

What is used as a drying agent in an experiment on the rusting process?

1. Copper chloride
2. Zinc Chloride
3. Anhydrous Calcium chloride
4. Anhydrous Calcium sulphate

Q.

When iron (Fe) is exposed to moist atmosphere for a long time, rust is formed which is a layer of a brown flaky substance. What is the chemical composition of this iron rust?

1. Iron oxide
2. Hydrated Iron oxide
3. Moisture and Oxygen
4. Iron

Q.

Read the following and answer any four questions from (i) to (v).

On the basis of reactivity of different metals with oxygen, water and acids as well as displacement reactions, the metals have been arranged in the decreasing order of their reactivities. This arrangement is known as activity series or reactivity series of metals.
The basis of reactivity is the tendency of metals to lose electrons. If a metal can lose electrons easily to form positive ions, it will react readily with other substances. Therefore, it will be a reactive metal. On the other hand, if a meal loses electrons less rapidly to form a positive ion, it will react slowly with other substances. Therefore, such a metal will be less reactive.

(i) Which of the following metals is less reactive than hydrogen?
(a) Copper (b) Zinc (c) Magnesium (d) Lead

(ii) Which of the following metals is more reactive than hydrogen?
(a) Mercury (b) Platinum (c) Iron (d) Gold

(iii) Which of the following metals reacts vigorously with oxygen?
(a) Zinc (b) Magnesium (c) Sodium (d) Copper

(iv) Which of the following represents the correct order of reactivity for the given metals?
(a) Na > Mg > Al > Cu (b) Mg > Na > Al > Cu
(c) Na > Mg > Cu > Al (d) Mg > Al > Na > Cu

(v) Hydrogen gas is not evolved when a metal reacts with nitric acid. It is because HNO₃, is a strong oxidising agent. It oxidises the H, produced to water and itself gets reduced to any of the nitrogen oxides (N, O, NO, NO₂). But _____________ and _____________ react with very dilute HNO₃ to evolve H₂ gas.
(a) Pb, Cu (b) Na, K (C) Mg, Mn (d) Al, Zn

Q. In the process of rusting, iron (Fe) reacts with which of the following substances that are present in the atmosphere?

1. $O_2$(air)
2. $H_{2}O$(moisture)
3. Both $O_2$ and $H_{2}O$
4. $F{e}_2{O}_3$

Q. What is the green colour coating that forms on copper when it is left open?

1. Copper sulphate
2. Copper carbonate
3. Copper chloride
4. Copper hydride

Q.

Formation of rust when iron is exposed to moist air is called ________.

1. Double displacement

2. Displacement

3. Corrosion

4. Neutralization

Q.

Corrosion is ________ type of reaction.

1. Double displacement

2. Displacement

3. Redox reaction

4. Neutralization

Q. The black coating formed on the surface of silver articles due to corrosion is ______.

1. silver sulphide
2. silver bicarbonate
3. silver oxide
4. silver carbonate

Q.

Metal X is used in the process of galvanisation. Metal Y is used to make household electrical wires. Metal X and metal Y combine to form alloy Z. Identify X, Y and Z.

1. X:- Tin

   Y:- Copper

   Z:- Bronze

2. X:- Zinc

   Y:- Copper

   Z:- Brass

3. X:- Magnesium

   Y:- Copper

   Z:- Bronze

4. X:- Magnesium

   Y:- Copper

   Z:- Brass

Q. Deterioration of a metal by chemical or electrochemical reaction with its environment is called _____.

1. corrosion
2. painting
3. polishing
4. galvanization