Factors Affecting Corrosion

Q.

Explain how rusting of iron is envisaged as setting up of an electrochemical cell.

Q.

What are the disadvantages of corrosion?

Q. Which of the following method cannot prevent corrosion?

1. Keeping the metal in sunlight
2. Covering the surface with paint, grease, oil etc.
3. Galvanisation
4. By cathodic protection

Q.

During the corrosion of metals, oxygen absorbed at

1. Anode

2. Cathode

3. Both anode and cathode

4. None is correct

Q. For the oxidation of iron, the entropy change is -549.45J/K.mol at 298K. Though it has negative entropy change, the reaction is spontaneous. Why?
The reaction is
4Fe+3O₂ gives 2Fe₂O₃

Q. Which of the following is/are the method(s) to prevent corrosion?

1. By cathodic protection
2. Galvanisation
3. Covering the surface with paint, grease, oil etc.
4. All of the above.

Q. Rusting of iron is an example of ________ reaction.

Q. The method(s) by which corrosion can be prevented is/are:

1. Keeping the metal in sunlight
2. Covering the surface with paint, grease, oil etc.
3. Galvanisation
4. By cathodic protection

Q.

Out of the following which is the factor that doesn't affect corrosion:

1. Temperature

2. Air and moisture

3. Presence of electrolytes

4. Reactivity of metal

Q.

Among the following nitrates, Lead nitrate, Silver nitrate and Ammonium nitrate; the one that decomposes without leaving any solid residue is

1. Lead nitrate

2. Ammonium nitrate

3. Silver nitrate

4. Sodium nitrate

Q. A shiny brown-coloured element 'X' on heating in air becomes black in colour. Name the element 'X'?

1. Sodium
2. Calcium
3. Copper
4. Aluminium

Q.

Rust is hydrated

1. alumininum oxide

2. copper oxide

3. iron oxide

4. silica

Q.

Corrosion of marble is also known as marble cancer.

1. True
2. False

Q.

How is corrosion different from rusting?

Q. Copper becomes green when exposed to moist air for a long period of time due to the

1. formation of a layer of cupric oxide on the surface of copper.
2. formation of a layer of basic carbonate of copper on the surface of copper.
3. none of the above.
4. formation of a layer of cupric hydroxide on the surface of copper.

Q. In corrosion of iron species acting as electrolyte is(1) Fe(OH)2 (2) H2CO3 (3)H2O (4) none of these

Q.

In electro-chemical corrosion of metals, the metal undergoing corrosion:

1. Becomes anode
2. Becomes cathode
3. Becomes inert
4. None is correct

Q. Answer the following questions:
1) Write down the chemistry involved in lead storage cell during charging and working.
2) What is cathodic protection? Write down the chemistry involved in rusting of iron .

Q.

What do you mean by rusting? Describe it with a proper chemical equation.

Q. In electrochemical corrosion. the metal undergoing corrosion :

1. acts as anode
2. acts as cathode
3. undergoes reduction
4. liquifies

Q. Corrosion of metals involves :

1. physical reaction
2. chemical reaction
3. both A and B
4. none of the above

Q. If copper is kept open in air, it slowly loses its shining brown surface and gains a green coating. It is due to the formation of:

1. $CuC{O}_3.Cu(OH{)}_2$
2. $CuC{O}_3$
3. $CuS{O}_4$
4. $CuO$

Q. Which of the following methods is not used to coat metallic elements to prevent corrosion?

1. Electroplating
2. Metal cladding
3. Metal spraying
4. None of the above

Q. In the atmosphere of industrial smog, copper corrodes to form:

1. Basic copper carbonate
2. Copper sulphide
3. Basic copper sulphate
4. Copper oxide

Q. What is meant by corrosion ? How corrosion is caused ? How it can be prevented ? What is the effect of corrosion on : (a) copper (b) Silver ?

Q. In rusting of iron, iron is oxidised and O${}_2$ is reduced. The no. of electrons used during reduction O${}_2$ are :

Q. The tarnishing of silver ornaments in the atmosphere is due to the formation of:

1. $A{g}_{2}O,A{g}_{2}S$
2. $AgN{O}_3,A{g}_{2}S$
3. $Ag$
4. $AgOH,A{g}_{2}C{O}_3$

Q. When Potassium Nitrate decomposes into Potassium Nitride and Oxygen ? balance the equation.

Q. The tarnishing of silver ornaments in atmosphere is due to:

1. $A{g}_{2}O$
2. $A{g}_{2}S$
3. $A{g}_{2}C{O}_3$
4. $A{g}_{2}S{O}_4$

Q. According to electrochemical theory of corrosion involves:

1. cathodic dissolution of metal
2. anodic dissolution of metal
3. anodic deposition of metal
4. cathodic deposition of metal