Textbook Solutions: Metallurgy | Science and Technology Class 10 (Maharashtra SSC Board) PDF Download

 Page 1


Metallurgy 
Exercise 
Q. 1. Write names. 
 
a. Alloy of sodium with mercury. 
b. Molecular formula of the common ore of aluminum. 
c. The oxide that forms salt and water by reacting with both acid and base. 
d. The device used for grinding an ore. 
e. The nonmetal having electrical conductivity. 
f. The reagent that dissolves noble metals. 
Answer : (a) Sodium amalgam, commonly denoted Na(Hg), is an alloy of mercury and 
sodium. 
(b) Bauxite. The molecular formula is Al2O3.H2O 
(c) Amphoteric oxides 
Eg. Al2O3 is an example of an amphoteric oxide 
(d) Ball mill, is often used for grinding an ore and getting enough size reduction. 
(e) Graphite is the only non-metal element that is a good conductor of electricity 
(f) Aqua Regia, 1:3 mixture of concentrated nitric and hydrochloric acids can dissolve 
noble metals such as gold, palladium, and platinum. 
Q. 2. Make pairs of substances and their properties 
 
 
Answer : 
Page 2


Metallurgy 
Exercise 
Q. 1. Write names. 
 
a. Alloy of sodium with mercury. 
b. Molecular formula of the common ore of aluminum. 
c. The oxide that forms salt and water by reacting with both acid and base. 
d. The device used for grinding an ore. 
e. The nonmetal having electrical conductivity. 
f. The reagent that dissolves noble metals. 
Answer : (a) Sodium amalgam, commonly denoted Na(Hg), is an alloy of mercury and 
sodium. 
(b) Bauxite. The molecular formula is Al2O3.H2O 
(c) Amphoteric oxides 
Eg. Al2O3 is an example of an amphoteric oxide 
(d) Ball mill, is often used for grinding an ore and getting enough size reduction. 
(e) Graphite is the only non-metal element that is a good conductor of electricity 
(f) Aqua Regia, 1:3 mixture of concentrated nitric and hydrochloric acids can dissolve 
noble metals such as gold, palladium, and platinum. 
Q. 2. Make pairs of substances and their properties 
 
 
Answer : 
 
Q. 3. Identify the pairs of metals and their ores from the following. 
 
 
Answer : 
 
Q. 4. Explain the terms. 
 
a. Metallurgy 
b. Ores 
c. Minerals 
d. Gangue 
Answer : (a) The process of extraction of the metals in pure form from their ores is 
termed as metallurgy. 
 
(b) The minerals or deposits from which the metals can be extracted are called ores. 
Page 3


Metallurgy 
Exercise 
Q. 1. Write names. 
 
a. Alloy of sodium with mercury. 
b. Molecular formula of the common ore of aluminum. 
c. The oxide that forms salt and water by reacting with both acid and base. 
d. The device used for grinding an ore. 
e. The nonmetal having electrical conductivity. 
f. The reagent that dissolves noble metals. 
Answer : (a) Sodium amalgam, commonly denoted Na(Hg), is an alloy of mercury and 
sodium. 
(b) Bauxite. The molecular formula is Al2O3.H2O 
(c) Amphoteric oxides 
Eg. Al2O3 is an example of an amphoteric oxide 
(d) Ball mill, is often used for grinding an ore and getting enough size reduction. 
(e) Graphite is the only non-metal element that is a good conductor of electricity 
(f) Aqua Regia, 1:3 mixture of concentrated nitric and hydrochloric acids can dissolve 
noble metals such as gold, palladium, and platinum. 
Q. 2. Make pairs of substances and their properties 
 
 
Answer : 
 
Q. 3. Identify the pairs of metals and their ores from the following. 
 
 
Answer : 
 
Q. 4. Explain the terms. 
 
a. Metallurgy 
b. Ores 
c. Minerals 
d. Gangue 
Answer : (a) The process of extraction of the metals in pure form from their ores is 
termed as metallurgy. 
 
(b) The minerals or deposits from which the metals can be extracted are called ores. 
(c) The naturally occurring compounds of metals along with their impurities is termed as 
minerals. 
(d) Ores contain metal compounds with some of the impurities such as sand and rocky 
materials and these impurities are called gangue. 
Q. 5. A. Write scientific reason. 
 
Lemon or tamarind is used for cleaning copper vessels turned greenish. 
Answer : Copper reacts with moist carbon dioxide in the air to form copper carbonate. 
The citric acid present in the lemon or tamarind neutralizes the basis copper carbonate 
and dissolves the layer. That is why tarnished copper vessels are cleaned with lemon or 
tamarind juice to give the surface of the copper vessel its characteristic shiny 
appearance. 
Q. 5. B. Write scientific reason. 
 
Generally, the ionic compounds have high melting points. 
Answer : Ionic compounds are formed from strong electrostatic interactions between 
ions, which result in higher melting points and electrical conductivity compared to 
covalent compounds. 
Q. 5. C. Write scientific reason. 
 
Sodium is always kept in kerosene. 
Answer : Sodium is a very reactive metal. It is kept in kerosene to prevent it from 
coming in contact with oxygen and moisture. If this happens, it will react with the 
moisture present in air and form sodium hydroxide. This is a strongly exothermic 
reaction, and a lot of heat is generated. 
Q. 5. D. Write scientific reason. 
 
Pine oil is used in froth flotation. 
Answer : Pine oil is used in froth flotation process because it does not have an affinity 
towards water (because of the hydrophobic chemicals as its constituents) and it attracts 
impurities which can be washed away. 
Q. 5. E. Write scientific reason. 
 
Anodes need to be replaced from time to time during the electrolysis of alumina. 
Page 4


Metallurgy 
Exercise 
Q. 1. Write names. 
 
a. Alloy of sodium with mercury. 
b. Molecular formula of the common ore of aluminum. 
c. The oxide that forms salt and water by reacting with both acid and base. 
d. The device used for grinding an ore. 
e. The nonmetal having electrical conductivity. 
f. The reagent that dissolves noble metals. 
Answer : (a) Sodium amalgam, commonly denoted Na(Hg), is an alloy of mercury and 
sodium. 
(b) Bauxite. The molecular formula is Al2O3.H2O 
(c) Amphoteric oxides 
Eg. Al2O3 is an example of an amphoteric oxide 
(d) Ball mill, is often used for grinding an ore and getting enough size reduction. 
(e) Graphite is the only non-metal element that is a good conductor of electricity 
(f) Aqua Regia, 1:3 mixture of concentrated nitric and hydrochloric acids can dissolve 
noble metals such as gold, palladium, and platinum. 
Q. 2. Make pairs of substances and their properties 
 
 
Answer : 
 
Q. 3. Identify the pairs of metals and their ores from the following. 
 
 
Answer : 
 
Q. 4. Explain the terms. 
 
a. Metallurgy 
b. Ores 
c. Minerals 
d. Gangue 
Answer : (a) The process of extraction of the metals in pure form from their ores is 
termed as metallurgy. 
 
(b) The minerals or deposits from which the metals can be extracted are called ores. 
(c) The naturally occurring compounds of metals along with their impurities is termed as 
minerals. 
(d) Ores contain metal compounds with some of the impurities such as sand and rocky 
materials and these impurities are called gangue. 
Q. 5. A. Write scientific reason. 
 
Lemon or tamarind is used for cleaning copper vessels turned greenish. 
Answer : Copper reacts with moist carbon dioxide in the air to form copper carbonate. 
The citric acid present in the lemon or tamarind neutralizes the basis copper carbonate 
and dissolves the layer. That is why tarnished copper vessels are cleaned with lemon or 
tamarind juice to give the surface of the copper vessel its characteristic shiny 
appearance. 
Q. 5. B. Write scientific reason. 
 
Generally, the ionic compounds have high melting points. 
Answer : Ionic compounds are formed from strong electrostatic interactions between 
ions, which result in higher melting points and electrical conductivity compared to 
covalent compounds. 
Q. 5. C. Write scientific reason. 
 
Sodium is always kept in kerosene. 
Answer : Sodium is a very reactive metal. It is kept in kerosene to prevent it from 
coming in contact with oxygen and moisture. If this happens, it will react with the 
moisture present in air and form sodium hydroxide. This is a strongly exothermic 
reaction, and a lot of heat is generated. 
Q. 5. D. Write scientific reason. 
 
Pine oil is used in froth flotation. 
Answer : Pine oil is used in froth flotation process because it does not have an affinity 
towards water (because of the hydrophobic chemicals as its constituents) and it attracts 
impurities which can be washed away. 
Q. 5. E. Write scientific reason. 
 
Anodes need to be replaced from time to time during the electrolysis of alumina. 
Answer : This is because over time the graphite anode gets degraded and loses its 
ability to act as an electrode. Also, more impurities will stick to the electrode. 
Q. 6. When a copper coin is dipped in silver nitrate solution, a glitter appears on 
the coin after some time. Why does this happen? Write the chemical equation. 
Answer : When Copper is dipped in silver nitrate solution, copper nitrate and silver 
metal are formed. A shining white deposit of silver metal is formed on the copper coin, 
which makes it glitter for some time. 
 
eq: 
 
Q. 7. The electronic configuration of metal ‘A’ is 2,8,1 and that of metal ‘B’ is 
2,8,8,2. Which of the two metals is more reactive? Write their reaction with dilute 
hydrochloric acid. 
Answer : From the configuration, 
Metal A is Sodium or Na-2,8,1 
Metal B is Calcium or Ca-2,8,8,1 
Metal A i.e Sodium is more reactive than Calcium. Sodium metal reactive than calcium 
and it even reacts when kept open in the air. 
Reaction With dil.HCl: 
Sodium reacts vigorously with dilute hydrochloric acid to form sodium chlorides and 
hydrogen. 
 
Calcium reacts less vigorously to form calcium chloride and hydrogen gas. 
 
Q. 8. A. Draw a neat labelled diagram. 
 
Magnetic separation method. 
Answer : 
 
 
Page 5


Metallurgy 
Exercise 
Q. 1. Write names. 
 
a. Alloy of sodium with mercury. 
b. Molecular formula of the common ore of aluminum. 
c. The oxide that forms salt and water by reacting with both acid and base. 
d. The device used for grinding an ore. 
e. The nonmetal having electrical conductivity. 
f. The reagent that dissolves noble metals. 
Answer : (a) Sodium amalgam, commonly denoted Na(Hg), is an alloy of mercury and 
sodium. 
(b) Bauxite. The molecular formula is Al2O3.H2O 
(c) Amphoteric oxides 
Eg. Al2O3 is an example of an amphoteric oxide 
(d) Ball mill, is often used for grinding an ore and getting enough size reduction. 
(e) Graphite is the only non-metal element that is a good conductor of electricity 
(f) Aqua Regia, 1:3 mixture of concentrated nitric and hydrochloric acids can dissolve 
noble metals such as gold, palladium, and platinum. 
Q. 2. Make pairs of substances and their properties 
 
 
Answer : 
 
Q. 3. Identify the pairs of metals and their ores from the following. 
 
 
Answer : 
 
Q. 4. Explain the terms. 
 
a. Metallurgy 
b. Ores 
c. Minerals 
d. Gangue 
Answer : (a) The process of extraction of the metals in pure form from their ores is 
termed as metallurgy. 
 
(b) The minerals or deposits from which the metals can be extracted are called ores. 
(c) The naturally occurring compounds of metals along with their impurities is termed as 
minerals. 
(d) Ores contain metal compounds with some of the impurities such as sand and rocky 
materials and these impurities are called gangue. 
Q. 5. A. Write scientific reason. 
 
Lemon or tamarind is used for cleaning copper vessels turned greenish. 
Answer : Copper reacts with moist carbon dioxide in the air to form copper carbonate. 
The citric acid present in the lemon or tamarind neutralizes the basis copper carbonate 
and dissolves the layer. That is why tarnished copper vessels are cleaned with lemon or 
tamarind juice to give the surface of the copper vessel its characteristic shiny 
appearance. 
Q. 5. B. Write scientific reason. 
 
Generally, the ionic compounds have high melting points. 
Answer : Ionic compounds are formed from strong electrostatic interactions between 
ions, which result in higher melting points and electrical conductivity compared to 
covalent compounds. 
Q. 5. C. Write scientific reason. 
 
Sodium is always kept in kerosene. 
Answer : Sodium is a very reactive metal. It is kept in kerosene to prevent it from 
coming in contact with oxygen and moisture. If this happens, it will react with the 
moisture present in air and form sodium hydroxide. This is a strongly exothermic 
reaction, and a lot of heat is generated. 
Q. 5. D. Write scientific reason. 
 
Pine oil is used in froth flotation. 
Answer : Pine oil is used in froth flotation process because it does not have an affinity 
towards water (because of the hydrophobic chemicals as its constituents) and it attracts 
impurities which can be washed away. 
Q. 5. E. Write scientific reason. 
 
Anodes need to be replaced from time to time during the electrolysis of alumina. 
Answer : This is because over time the graphite anode gets degraded and loses its 
ability to act as an electrode. Also, more impurities will stick to the electrode. 
Q. 6. When a copper coin is dipped in silver nitrate solution, a glitter appears on 
the coin after some time. Why does this happen? Write the chemical equation. 
Answer : When Copper is dipped in silver nitrate solution, copper nitrate and silver 
metal are formed. A shining white deposit of silver metal is formed on the copper coin, 
which makes it glitter for some time. 
 
eq: 
 
Q. 7. The electronic configuration of metal ‘A’ is 2,8,1 and that of metal ‘B’ is 
2,8,8,2. Which of the two metals is more reactive? Write their reaction with dilute 
hydrochloric acid. 
Answer : From the configuration, 
Metal A is Sodium or Na-2,8,1 
Metal B is Calcium or Ca-2,8,8,1 
Metal A i.e Sodium is more reactive than Calcium. Sodium metal reactive than calcium 
and it even reacts when kept open in the air. 
Reaction With dil.HCl: 
Sodium reacts vigorously with dilute hydrochloric acid to form sodium chlorides and 
hydrogen. 
 
Calcium reacts less vigorously to form calcium chloride and hydrogen gas. 
 
Q. 8. A. Draw a neat labelled diagram. 
 
Magnetic separation method. 
Answer : 
 
 
 
Q. 8. B. Draw a neat labelled diagram. 
 
Froth floatation method. 
Answer :  
 
Q. 8. C. Draw a neat labelled diagram. 
 
Electrolytic reduction of alumina. 
Answer :