Selina Textbook Solutions: Study of Acids, Bases and Salts | Chemistry Class 10 ICSE PDF Download

 Page 1


Class X Chapter 03 – Acids, Bases and Salts  Chemistry 
_____________________________________________________________________________ 
 
                  
 
INTEXT - QUESTION- 1 
 
Question 1: 
What do you understand by the terms, acid and base? 
Solution 1: 
(a) Acids are defined as compounds which contain one or more hydrogen atoms, and when 
dissolved in water, they produce hydronium ions (H3O
+
), the only positively charged ions. 
(b) Hydronium ion 
(c) H3O
+
 
 
 
Question 2: 
Explain the formation of hydronium ion. Write the ionization of sulphuric acid showing the 
formation of hydronium ion. 
Solution 2: 
Hydronium ions: They are formed by the reaction of H
+
 (from acid) and water. It reacts with 
water to form H3O
+
 (Hydronium ion). 
H
+ 
+ H2O H3O
+ 
Ionization of sulphuric acid showing the formation of hydronium ion: 
  
 
 
Question 3: 
Water is never added to acid in order to dilute it why? 
Solution 3: 
If water is added to a concentrated acid, the heat generated causes the mixture to splash out and 
cause severe burns. Thus, water is never added to acid in order to dilute it.  
 
 
Question 4:  
Define the term ‘basicity’ of an acid. Give the basicity of: nitric acid, sulphuric acid and 
phosphoric acid.  
Solution 4: 
Basicity: The basicity of an acid is defined as the number of hydronium ions (H3O
+
) that can be 
produced by the ionization of one molecule of that acid in aqueous solution. 
 
Page 2


Class X Chapter 03 – Acids, Bases and Salts  Chemistry 
_____________________________________________________________________________ 
 
                  
 
INTEXT - QUESTION- 1 
 
Question 1: 
What do you understand by the terms, acid and base? 
Solution 1: 
(a) Acids are defined as compounds which contain one or more hydrogen atoms, and when 
dissolved in water, they produce hydronium ions (H3O
+
), the only positively charged ions. 
(b) Hydronium ion 
(c) H3O
+
 
 
 
Question 2: 
Explain the formation of hydronium ion. Write the ionization of sulphuric acid showing the 
formation of hydronium ion. 
Solution 2: 
Hydronium ions: They are formed by the reaction of H
+
 (from acid) and water. It reacts with 
water to form H3O
+
 (Hydronium ion). 
H
+ 
+ H2O H3O
+ 
Ionization of sulphuric acid showing the formation of hydronium ion: 
  
 
 
Question 3: 
Water is never added to acid in order to dilute it why? 
Solution 3: 
If water is added to a concentrated acid, the heat generated causes the mixture to splash out and 
cause severe burns. Thus, water is never added to acid in order to dilute it.  
 
 
Question 4:  
Define the term ‘basicity’ of an acid. Give the basicity of: nitric acid, sulphuric acid and 
phosphoric acid.  
Solution 4: 
Basicity: The basicity of an acid is defined as the number of hydronium ions (H3O
+
) that can be 
produced by the ionization of one molecule of that acid in aqueous solution. 
 
Class X Chapter 03 – Acids, Bases and Salts  Chemistry 
_____________________________________________________________________________ 
 
The basicity of following compounds are: 
Nitric acid: Basicity = 1 
Sulphuric acid: Basicity =2 
Phosphoric acid: Basicity =3  
 
 
Question 5: 
Give two examples of each of the following: 
(a) oxy-acid 
(b) hydracids 
(c) monobasic acid 
(d) dibasic acid 
(e) tribasic acid 
Solution 5: 
(a) Oxyacids: - HNO3, H2SO4 
(b) Hydracid:- HCl, HBr 
(c) Monobasic acid:- HCl, HBr 
(d) Dibasic acid: - H2SO4 , H2CO3 
(e) Tribasic acid:- H3PO4, H3PO3 
 
 
Question 6: 
Name the: 
(a) acidic anhydride of the following acids: 
(i) sulphurous acid 
(ii) nitric acid 
(iii) phosphoric acid 
(iv) carbonic acid 
(b) acids present in vinegar, grapes and lemon 
(c)  (i) ion that turns blue litmus red, 
      (ii) ion that turns red litmus blue. 
Solution 6: 
(a) The anhydride of following acids are: 
(i) Sulphurous acid: SO2 
(ii) Nitric acid: N2O5 
(iii) Phosphoric acid: P2O5 
(iv) Carbonic acid : CO2 
(b) Acids present in following are: 
Page 3


Class X Chapter 03 – Acids, Bases and Salts  Chemistry 
_____________________________________________________________________________ 
 
                  
 
INTEXT - QUESTION- 1 
 
Question 1: 
What do you understand by the terms, acid and base? 
Solution 1: 
(a) Acids are defined as compounds which contain one or more hydrogen atoms, and when 
dissolved in water, they produce hydronium ions (H3O
+
), the only positively charged ions. 
(b) Hydronium ion 
(c) H3O
+
 
 
 
Question 2: 
Explain the formation of hydronium ion. Write the ionization of sulphuric acid showing the 
formation of hydronium ion. 
Solution 2: 
Hydronium ions: They are formed by the reaction of H
+
 (from acid) and water. It reacts with 
water to form H3O
+
 (Hydronium ion). 
H
+ 
+ H2O H3O
+ 
Ionization of sulphuric acid showing the formation of hydronium ion: 
  
 
 
Question 3: 
Water is never added to acid in order to dilute it why? 
Solution 3: 
If water is added to a concentrated acid, the heat generated causes the mixture to splash out and 
cause severe burns. Thus, water is never added to acid in order to dilute it.  
 
 
Question 4:  
Define the term ‘basicity’ of an acid. Give the basicity of: nitric acid, sulphuric acid and 
phosphoric acid.  
Solution 4: 
Basicity: The basicity of an acid is defined as the number of hydronium ions (H3O
+
) that can be 
produced by the ionization of one molecule of that acid in aqueous solution. 
 
Class X Chapter 03 – Acids, Bases and Salts  Chemistry 
_____________________________________________________________________________ 
 
The basicity of following compounds are: 
Nitric acid: Basicity = 1 
Sulphuric acid: Basicity =2 
Phosphoric acid: Basicity =3  
 
 
Question 5: 
Give two examples of each of the following: 
(a) oxy-acid 
(b) hydracids 
(c) monobasic acid 
(d) dibasic acid 
(e) tribasic acid 
Solution 5: 
(a) Oxyacids: - HNO3, H2SO4 
(b) Hydracid:- HCl, HBr 
(c) Monobasic acid:- HCl, HBr 
(d) Dibasic acid: - H2SO4 , H2CO3 
(e) Tribasic acid:- H3PO4, H3PO3 
 
 
Question 6: 
Name the: 
(a) acidic anhydride of the following acids: 
(i) sulphurous acid 
(ii) nitric acid 
(iii) phosphoric acid 
(iv) carbonic acid 
(b) acids present in vinegar, grapes and lemon 
(c)  (i) ion that turns blue litmus red, 
      (ii) ion that turns red litmus blue. 
Solution 6: 
(a) The anhydride of following acids are: 
(i) Sulphurous acid: SO2 
(ii) Nitric acid: N2O5 
(iii) Phosphoric acid: P2O5 
(iv) Carbonic acid : CO2 
(b) Acids present in following are: 
Class X Chapter 03 – Acids, Bases and Salts  Chemistry 
_____________________________________________________________________________ 
 
Vinegar: Acetic acid 
Grapes: Tartaric acid and Malic acid 
Lemon: Citric acid 
 
(c) (i) H
+
 ion turns blue litmus red. 
     (ii) OH
-
 ion turns red litmus blue. 
 
 
Question 7: 
What do you understand by the statement ‘acetic acid is a monobasic acid? 
Solution 7: 
Acetic acid is a monobasic acid which on ionization in water produce one hydronium ion per 
molecule of the acid.  
 
 
Question 8: 
(a) Give a balanced equation for reaction of nitrogen dioxide with water. 
(b) How many types of salts does dibasic acid produce when it reacts with caustic   soda 
solution? Give equation(s)  
Solution 8: 
(a) 2NO2 + H2O ? HNO2 + HNO3 
(b) Two types of salts are produced when dibasic acid reacts with caustic soda. One is acidic 
salt and other normal salt. 
 
Acid salts: 
H2SO4 + NaOH ? NaHSO4 + H2O 
Normal salts: 
H2SO4 + 2NaOH ? Na2SO4 + 2H2O  
 
 
Question 9: 
Carbonic acid gives an acid salt but hydrochloric acid does not. Explain.  
Solution 9: 
The strength of an acid is the extent to which the acid ionizes or dissociates in water. 
The strength of an acid depends on the degree of ionization and concentration of hydronium ions 
[H3O
+
] produced by that acid in aqueous solution.  
 
Page 4


Class X Chapter 03 – Acids, Bases and Salts  Chemistry 
_____________________________________________________________________________ 
 
                  
 
INTEXT - QUESTION- 1 
 
Question 1: 
What do you understand by the terms, acid and base? 
Solution 1: 
(a) Acids are defined as compounds which contain one or more hydrogen atoms, and when 
dissolved in water, they produce hydronium ions (H3O
+
), the only positively charged ions. 
(b) Hydronium ion 
(c) H3O
+
 
 
 
Question 2: 
Explain the formation of hydronium ion. Write the ionization of sulphuric acid showing the 
formation of hydronium ion. 
Solution 2: 
Hydronium ions: They are formed by the reaction of H
+
 (from acid) and water. It reacts with 
water to form H3O
+
 (Hydronium ion). 
H
+ 
+ H2O H3O
+ 
Ionization of sulphuric acid showing the formation of hydronium ion: 
  
 
 
Question 3: 
Water is never added to acid in order to dilute it why? 
Solution 3: 
If water is added to a concentrated acid, the heat generated causes the mixture to splash out and 
cause severe burns. Thus, water is never added to acid in order to dilute it.  
 
 
Question 4:  
Define the term ‘basicity’ of an acid. Give the basicity of: nitric acid, sulphuric acid and 
phosphoric acid.  
Solution 4: 
Basicity: The basicity of an acid is defined as the number of hydronium ions (H3O
+
) that can be 
produced by the ionization of one molecule of that acid in aqueous solution. 
 
Class X Chapter 03 – Acids, Bases and Salts  Chemistry 
_____________________________________________________________________________ 
 
The basicity of following compounds are: 
Nitric acid: Basicity = 1 
Sulphuric acid: Basicity =2 
Phosphoric acid: Basicity =3  
 
 
Question 5: 
Give two examples of each of the following: 
(a) oxy-acid 
(b) hydracids 
(c) monobasic acid 
(d) dibasic acid 
(e) tribasic acid 
Solution 5: 
(a) Oxyacids: - HNO3, H2SO4 
(b) Hydracid:- HCl, HBr 
(c) Monobasic acid:- HCl, HBr 
(d) Dibasic acid: - H2SO4 , H2CO3 
(e) Tribasic acid:- H3PO4, H3PO3 
 
 
Question 6: 
Name the: 
(a) acidic anhydride of the following acids: 
(i) sulphurous acid 
(ii) nitric acid 
(iii) phosphoric acid 
(iv) carbonic acid 
(b) acids present in vinegar, grapes and lemon 
(c)  (i) ion that turns blue litmus red, 
      (ii) ion that turns red litmus blue. 
Solution 6: 
(a) The anhydride of following acids are: 
(i) Sulphurous acid: SO2 
(ii) Nitric acid: N2O5 
(iii) Phosphoric acid: P2O5 
(iv) Carbonic acid : CO2 
(b) Acids present in following are: 
Class X Chapter 03 – Acids, Bases and Salts  Chemistry 
_____________________________________________________________________________ 
 
Vinegar: Acetic acid 
Grapes: Tartaric acid and Malic acid 
Lemon: Citric acid 
 
(c) (i) H
+
 ion turns blue litmus red. 
     (ii) OH
-
 ion turns red litmus blue. 
 
 
Question 7: 
What do you understand by the statement ‘acetic acid is a monobasic acid? 
Solution 7: 
Acetic acid is a monobasic acid which on ionization in water produce one hydronium ion per 
molecule of the acid.  
 
 
Question 8: 
(a) Give a balanced equation for reaction of nitrogen dioxide with water. 
(b) How many types of salts does dibasic acid produce when it reacts with caustic   soda 
solution? Give equation(s)  
Solution 8: 
(a) 2NO2 + H2O ? HNO2 + HNO3 
(b) Two types of salts are produced when dibasic acid reacts with caustic soda. One is acidic 
salt and other normal salt. 
 
Acid salts: 
H2SO4 + NaOH ? NaHSO4 + H2O 
Normal salts: 
H2SO4 + 2NaOH ? Na2SO4 + 2H2O  
 
 
Question 9: 
Carbonic acid gives an acid salt but hydrochloric acid does not. Explain.  
Solution 9: 
The strength of an acid is the extent to which the acid ionizes or dissociates in water. 
The strength of an acid depends on the degree of ionization and concentration of hydronium ions 
[H3O
+
] produced by that acid in aqueous solution.  
 
Class X Chapter 03 – Acids, Bases and Salts  Chemistry 
_____________________________________________________________________________ 
 
 
Question 10: 
What do you understand by the strength of an acid? On which factor does the strength of an acid 
depend? 
Solution 10: 
(a) Carbonic acid is a dibasic acid with two replaceable hydrogen ions; therefore it forms one 
acid salt or one normal salt. 
Hydrochloric acid is a monobasic acid with one replaceable hydrogen ion and so forms only 
one normal salt. 
 
(b) Strength of an acid is the measure of concentration of hydronium ions it produces in its 
aqueous solution. Dil. HCl produces high concentration of hydronium ion compared to that 
of concentrated acetic acid. Thus, dil. HCl is stronger acid than highly concentrated acetic 
acid. 
 
(c) H3PO3 is not a tribasic acid because in oxyacids of phosphorus, hydrogen atoms which are 
attached to oxygen atoms are replaceable. Hydrogen atoms directly bonded to phosphorus 
atoms are not replaceable. 
 
 
 
(d) The salt produced is insoluble in the solution so the reaction does not proceed. Hence, we 
do not expect lead carbonate to react with hydrochloric acid. 
 
(e) NO2 is called double acid anhydride because two acids – nitrous acid and nitric acid – are 
formed when it reacts with water. 
       2NO2 + H2O ? HNO2 + HNO3  
 
 
Question 11: 
Dil. HCl acid is stronger than highly concentrated acetic acid. Explain. 
Solution 11: 
Acid rain is a by-product of a variety of human activities which release oxides of sulphur and 
nitrogen in the atmosphere. Burning of fossil fuels, coal, oil, petrol and diesel produces sulphur 
Page 5


Class X Chapter 03 – Acids, Bases and Salts  Chemistry 
_____________________________________________________________________________ 
 
                  
 
INTEXT - QUESTION- 1 
 
Question 1: 
What do you understand by the terms, acid and base? 
Solution 1: 
(a) Acids are defined as compounds which contain one or more hydrogen atoms, and when 
dissolved in water, they produce hydronium ions (H3O
+
), the only positively charged ions. 
(b) Hydronium ion 
(c) H3O
+
 
 
 
Question 2: 
Explain the formation of hydronium ion. Write the ionization of sulphuric acid showing the 
formation of hydronium ion. 
Solution 2: 
Hydronium ions: They are formed by the reaction of H
+
 (from acid) and water. It reacts with 
water to form H3O
+
 (Hydronium ion). 
H
+ 
+ H2O H3O
+ 
Ionization of sulphuric acid showing the formation of hydronium ion: 
  
 
 
Question 3: 
Water is never added to acid in order to dilute it why? 
Solution 3: 
If water is added to a concentrated acid, the heat generated causes the mixture to splash out and 
cause severe burns. Thus, water is never added to acid in order to dilute it.  
 
 
Question 4:  
Define the term ‘basicity’ of an acid. Give the basicity of: nitric acid, sulphuric acid and 
phosphoric acid.  
Solution 4: 
Basicity: The basicity of an acid is defined as the number of hydronium ions (H3O
+
) that can be 
produced by the ionization of one molecule of that acid in aqueous solution. 
 
Class X Chapter 03 – Acids, Bases and Salts  Chemistry 
_____________________________________________________________________________ 
 
The basicity of following compounds are: 
Nitric acid: Basicity = 1 
Sulphuric acid: Basicity =2 
Phosphoric acid: Basicity =3  
 
 
Question 5: 
Give two examples of each of the following: 
(a) oxy-acid 
(b) hydracids 
(c) monobasic acid 
(d) dibasic acid 
(e) tribasic acid 
Solution 5: 
(a) Oxyacids: - HNO3, H2SO4 
(b) Hydracid:- HCl, HBr 
(c) Monobasic acid:- HCl, HBr 
(d) Dibasic acid: - H2SO4 , H2CO3 
(e) Tribasic acid:- H3PO4, H3PO3 
 
 
Question 6: 
Name the: 
(a) acidic anhydride of the following acids: 
(i) sulphurous acid 
(ii) nitric acid 
(iii) phosphoric acid 
(iv) carbonic acid 
(b) acids present in vinegar, grapes and lemon 
(c)  (i) ion that turns blue litmus red, 
      (ii) ion that turns red litmus blue. 
Solution 6: 
(a) The anhydride of following acids are: 
(i) Sulphurous acid: SO2 
(ii) Nitric acid: N2O5 
(iii) Phosphoric acid: P2O5 
(iv) Carbonic acid : CO2 
(b) Acids present in following are: 
Class X Chapter 03 – Acids, Bases and Salts  Chemistry 
_____________________________________________________________________________ 
 
Vinegar: Acetic acid 
Grapes: Tartaric acid and Malic acid 
Lemon: Citric acid 
 
(c) (i) H
+
 ion turns blue litmus red. 
     (ii) OH
-
 ion turns red litmus blue. 
 
 
Question 7: 
What do you understand by the statement ‘acetic acid is a monobasic acid? 
Solution 7: 
Acetic acid is a monobasic acid which on ionization in water produce one hydronium ion per 
molecule of the acid.  
 
 
Question 8: 
(a) Give a balanced equation for reaction of nitrogen dioxide with water. 
(b) How many types of salts does dibasic acid produce when it reacts with caustic   soda 
solution? Give equation(s)  
Solution 8: 
(a) 2NO2 + H2O ? HNO2 + HNO3 
(b) Two types of salts are produced when dibasic acid reacts with caustic soda. One is acidic 
salt and other normal salt. 
 
Acid salts: 
H2SO4 + NaOH ? NaHSO4 + H2O 
Normal salts: 
H2SO4 + 2NaOH ? Na2SO4 + 2H2O  
 
 
Question 9: 
Carbonic acid gives an acid salt but hydrochloric acid does not. Explain.  
Solution 9: 
The strength of an acid is the extent to which the acid ionizes or dissociates in water. 
The strength of an acid depends on the degree of ionization and concentration of hydronium ions 
[H3O
+
] produced by that acid in aqueous solution.  
 
Class X Chapter 03 – Acids, Bases and Salts  Chemistry 
_____________________________________________________________________________ 
 
 
Question 10: 
What do you understand by the strength of an acid? On which factor does the strength of an acid 
depend? 
Solution 10: 
(a) Carbonic acid is a dibasic acid with two replaceable hydrogen ions; therefore it forms one 
acid salt or one normal salt. 
Hydrochloric acid is a monobasic acid with one replaceable hydrogen ion and so forms only 
one normal salt. 
 
(b) Strength of an acid is the measure of concentration of hydronium ions it produces in its 
aqueous solution. Dil. HCl produces high concentration of hydronium ion compared to that 
of concentrated acetic acid. Thus, dil. HCl is stronger acid than highly concentrated acetic 
acid. 
 
(c) H3PO3 is not a tribasic acid because in oxyacids of phosphorus, hydrogen atoms which are 
attached to oxygen atoms are replaceable. Hydrogen atoms directly bonded to phosphorus 
atoms are not replaceable. 
 
 
 
(d) The salt produced is insoluble in the solution so the reaction does not proceed. Hence, we 
do not expect lead carbonate to react with hydrochloric acid. 
 
(e) NO2 is called double acid anhydride because two acids – nitrous acid and nitric acid – are 
formed when it reacts with water. 
       2NO2 + H2O ? HNO2 + HNO3  
 
 
Question 11: 
Dil. HCl acid is stronger than highly concentrated acetic acid. Explain. 
Solution 11: 
Acid rain is a by-product of a variety of human activities which release oxides of sulphur and 
nitrogen in the atmosphere. Burning of fossil fuels, coal, oil, petrol and diesel produces sulphur 
Class X Chapter 03 – Acids, Bases and Salts  Chemistry 
_____________________________________________________________________________ 
 
dioxide and nitrogen oxide which pollute the air. Polluted air also contains many oxidising 
agents which produce oxygen because of excessive heat. This oxygen combines with the oxides 
of sulphur and nitrogen and rain water to form acids. 
 
2SO2 + O2 + 2H2O ? 2H2SO4 
4NO2 + O2 + 2H2O ? 4HNO3  
 
 
Question 12: 
How is an acid prepared from a  
(a) Non-metal  
(b) Salt?  
Give an equation for each. 
Solution 12: 
Acids are prepared from non-metals by their oxidation. For example : 
Sulphur or phosphorus is oxidized by conc. Nitric acid to form sulphuric acid or phosphoric 
acid. 
 
S + 6HNO3                     H2SO4  + 2H2O + 6NO2 
P + 5HNO3                    H3PO4  + H2O + 5NO2 
 
Acids are prepared from salt by displacement reaction. For example : 
Nitric acid is prepared by using H2SO4 and sodium chloride. 
 
NaCl + H2SO4                     NaHSO4 + HNO3  
 
Question 13: 
Name an acid used: 
(a) to flavor and preserve food, 
(b) in a drink, 
(c) to remove ink spots, 
(d) as an eyewash 
Solution 13: 
(a)  SO2 +H2O               H2SO3 
(b)  P2O5 +3H2O              2H3PO4 
(c)  CO2 + H2O              H2CO3 
(d) SO3 + H2O              H2SO4