Metallurgy
1. Which metals occur in native, and which occur in the combined state?
Metals like silver, gold, platinum, etc., are less reactive and occur in the native state
whereas metals like copper, aluminium, sodium etc., are highly active and occur in the
combined state with halogens, sulphur, oxygen, etc. e.g., copper pyrites (CuFeS2),
bauxite
(Al2O3), common salt (NaCl), etc.
2. Compare the properties of metals and non metals with respect to
(i) Hardness and (ii) Tensile strength
Hardness: Metals are hard except Na and K, which are soft metals.
Non metals are soft except diamond, which is hard.
Tensile strength: Metals have high tensile strength.
Non metals have low tensile strength.
3. Explain why metals exhibit metallic lustre.
The bright lustre of metals is due to their ability to reflect the incident light from
their face and the surface acquires a shining appearance.
4. Give examples of the metals which are lustrous.
Iron, silver, magnesium, aluminium etc. appear as white whereas gold is yellow and
copper is reddish brown in appearance.
5. Explain why metals are hard.
Metals are hard because of strong forces of attraction between the metal atoms.
6. Give examples of metals which are soft.
Sodium and potassium are soft metals.
, 7. Magnesium and aluminium are not soft metals. Why?
Because they cannot be cut with a knife.
8. What is the action of water on (i) Sodium and (ii) Magnesium?
(i) Sodium and potassium react vigorously with cold water forming their hydroxides and
liberating H2 gas.
2 Na + 2 H2 O 2 NaOH + H2
2 K + 2 H2 O 2 KOH + H2
(ii) Magnesium on reaction with water forms magnesium oxide and libertes hydrogen
Mg + H2 O MgO + H2
9. What are hydrides? Give and example.
These are the compounds which contain hydrogen as the electronegative element.
Example: Sodium hydride, NaH, Calcium hydride CaH2.
10. What are minerals?
The various compounds of metals, which occur in nature and are obtained
by mining, are called minerals.
11. What are ores? Give an example.
Ores are minerals from which metals can be conveniently and economically
Extracted. E.g., Haematite is the ore of iron because it is used in the extraction of iron.
12. What do you understand by the term metallurgy?
The process of extraction of pure metals from their ores is called metallurgy.
13. What is meant by ‘enrichment or ores’?
The process used for removing the gangue from the ore are based on the
difference between the physical or chemical properties of the gangue and the ore.
1. Which metals occur in native, and which occur in the combined state?
Metals like silver, gold, platinum, etc., are less reactive and occur in the native state
whereas metals like copper, aluminium, sodium etc., are highly active and occur in the
combined state with halogens, sulphur, oxygen, etc. e.g., copper pyrites (CuFeS2),
bauxite
(Al2O3), common salt (NaCl), etc.
2. Compare the properties of metals and non metals with respect to
(i) Hardness and (ii) Tensile strength
Hardness: Metals are hard except Na and K, which are soft metals.
Non metals are soft except diamond, which is hard.
Tensile strength: Metals have high tensile strength.
Non metals have low tensile strength.
3. Explain why metals exhibit metallic lustre.
The bright lustre of metals is due to their ability to reflect the incident light from
their face and the surface acquires a shining appearance.
4. Give examples of the metals which are lustrous.
Iron, silver, magnesium, aluminium etc. appear as white whereas gold is yellow and
copper is reddish brown in appearance.
5. Explain why metals are hard.
Metals are hard because of strong forces of attraction between the metal atoms.
6. Give examples of metals which are soft.
Sodium and potassium are soft metals.
, 7. Magnesium and aluminium are not soft metals. Why?
Because they cannot be cut with a knife.
8. What is the action of water on (i) Sodium and (ii) Magnesium?
(i) Sodium and potassium react vigorously with cold water forming their hydroxides and
liberating H2 gas.
2 Na + 2 H2 O 2 NaOH + H2
2 K + 2 H2 O 2 KOH + H2
(ii) Magnesium on reaction with water forms magnesium oxide and libertes hydrogen
Mg + H2 O MgO + H2
9. What are hydrides? Give and example.
These are the compounds which contain hydrogen as the electronegative element.
Example: Sodium hydride, NaH, Calcium hydride CaH2.
10. What are minerals?
The various compounds of metals, which occur in nature and are obtained
by mining, are called minerals.
11. What are ores? Give an example.
Ores are minerals from which metals can be conveniently and economically
Extracted. E.g., Haematite is the ore of iron because it is used in the extraction of iron.
12. What do you understand by the term metallurgy?
The process of extraction of pure metals from their ores is called metallurgy.
13. What is meant by ‘enrichment or ores’?
The process used for removing the gangue from the ore are based on the
difference between the physical or chemical properties of the gangue and the ore.
