Questions On Principles of Metallurgy Class 10

 

1. What are the conditions for the corrosion of iron ? (OR)

 State the conditions under which iron articles rust ? (OR)

 Do you know why corrosion occurs ?

Ans: Corrosion of iron occurs in presence of water and air.

2. Bronze is an alloy of which metals ?

Ans: Copper and tin

3. What are the salts present in Sea water ?

Ans: Sodium chloride and magnesium chloride etc.

4. What is the main ore of Aluminium ?

Ans: Bauxite

5. Give a daily life example for corrosion.

Ans: 1. The rusting of iron (iron oxide)

 2. Tarnishing of silver (silver sulphide)

6. Name the chemical, which is used for Prevention of corrosion.

Ans: Bisphenol

7. How is stainless steel made ?

Ans: When iron is mixed with nickel and chromium we get stainless steel.

8. The metal that occurs in the native form is ----------

 A) Pb B) Au C) Fe D) Hg

Ans: B) Au

9. The most abundant metal in the earth’s crust is ----------

 A) Silver B) Aluminium C) zinc D) iron

Ans: B) Aluminium 

One Mark Questions

1. How the metals are present in nature ?

Ans: 1. Some metals like gold (Au), silver (Ag) and copper (Cu) are available in nature in free state.

2. Other metals mostly are found in nature in the combined form.

2. We use P.V.C. pipes for water supply instead of metal pipes. Why ?

Ans: 1. P.V.C pipes do not rust.

2. So they are used for water supply instead of metal pipes. 

3. What are the conditions, under which iron articles rust ?

Ans: Corrosion (rusting) of iron occurs in presence of water and air.

4. What are the preventive methods do you take for rusting iron materials ?

Ans: 1. Covering the surface of iron materials with paint.

 2. Electroplating

5. List three metals that are found in nature in uncombined form.

Ans: 1. Gold (Au) 2. Silver (Ag) and 3. Copper (Cu).

6. Define Mineral.

Ans: Minerals: The elements or compounds of the metals which occur in nature in the earth crust are called minerals.

7. What is Ore ?

Ans: Ore: The minerals from which the metals are extracted without economical loss are called ores.

8. What is gangue ?

Ans: Gangue: The impurities like sand and clay are called gangue.

9. What is corrosion ?

Ans: Corrosion: When some metals are exposed to moisture, acids etc., they tarnish due to the formation of respective metal oxide on their surface. This process is called corrosion. 

Important Topics

● We use various metals for various purposes like gold and silver as jewellery, copper, iron, alluminium for making conducting wires and for making utensils etc.

● Metallurgy: “Metallurgy is the process of extraction of metals from their ores”.

● Bronze is an alloy of copper and tin.

● Now we have more than 75% metals among the elements available.

● The earth’s crust is the major source of metals.

● Sea water also contains some soluble salts such as sodium chloride and magnesium chloride etc.

● Some metals like gold (Au), silver (Ag) and copper (Cu) are available in nature in free state (native) as they are least reactive.

• Other metals mostly are found in nature in the combined form due to their more reactivity. 

● Minerals: The elements or compounds of the metals which occur in nature in the earth crust are called minerals.

● Ores: The minerals from which the metals are extracted without economical loss are called ores.

● Aluminium is profitably extracted from bauxite – which contains from 50 – 70 % of aluminium oxide.

● The metals like K, Na, Ca, Mg and Al are so reactive that they are never found in nature in free state.

● The metals like Zn, Fe, Pb etc., are moderately reactive. They are found in the earth crust mainly as oxides, sulphides and carbonates.

● Metals like Au, Ag are least reactive and they are found even in free state in nature.

● Gangue: The impurities like sand and clay are called gangue.

● Corrosion: When some metals are exposed to moisture, acids etc., they tarnish due to the formation of respective metal oxide on their surface. This process is called corrosion.

 Ex: The rusting of iron (iron oxide), tarnishing of silver (silver sulphide), development of green coating on copper (copper carbonate) and bronze are some of the examples of corrosion.

● Rusting of iron: The browning of iron, when left for sometime in moist air, is a process commonly known as rusting of iron.

● Corrosion of iron (rusting) occurs in presence of water and air. 

• corrosion may be considered as an electrochemical phenomenon.

● Prevention of corrosion:

1. Covering the surface with paint or by some chemicals (eg: bisphenol).

2. Electroplating: To cover the surface by other metals (Sn, Zn etc) that are inert or react themselves with atmosphere to save the object. This is generally done by electroplating.