Welcome to Class 10 Chemistry Chapter 10: Acid, Bases and Salts! This chapter is an essential part of your 10th class chemistry syllabus and helps students understand the basic concepts of acids, bases, pH scale, salts, and their types. Here, you will learn how acids release hydrogen ions, bases release hydroxide ions, and how the pH scale determines whether a solution is acidic, neutral, or basic. The chapter also explains how salts are formed through neutralization reactions and introduces different types of salts, including normal, acidic, basic, and double salts, along with their uses in daily life. This PDF also includes MCQs, Short Questions, and Long Questions, making it a complete and exam-oriented resource for students preparing for their chemistry exams.
Important MCQs – Chapter 10 Acid, Bases and Salts
1. Which of the following statements is true about strong acids and bases?
(a) They ionize partially in water
(b) They do not ionize at all
(c) They ionize completely in water ✅
(d) They produce salts directly
2. In Bronsted–Lowry concept, base is defined as:
(a) Electron donor
(b) Proton donor
(c) Proton acceptor ✅
(d) Proton neutralizer
3. According to Lewis concept, a base is:
(a) Electron pair acceptor
(b) Electron pair donor ✅
(c) Proton donor
(d) Ion producer in water
4. Which of the following is a normal salt?
(a) NaHSO₄
(b) NH₄Cl
(c) NaCl ✅
(d) Al(OH)₂Cl
5. Which of the following is a Bronsted–Lowry base in the reaction?
HCl(aq) + NH₃(aq) ⇒ NH₄⁺(aq) + Cl⁻(aq)
(a) HCl
(b) NH₄⁺
(c) NH₃ ✅
(d) Cl⁻
6. Which of the following is a limitation of Bronsted–Lowry concept?
(a) It does not explain redox reactions
(b) It only applies to aqueous solutions
(c) It excludes substances like SO₃ that act as acids without donating protons ✅
(d) It does not recognize conjugate pairs
7. Which of the following is a Lewis acid?
(a) NH₃
(b) Cl⁻
(c) BF₃ ✅
(d) OH⁻
8. The Brønsted–Lowry concept is applicable in:
(a) Only aqueous solutions
(b) Only gaseous states
(c) Non-aqueous solutions ✅
(d) Metallic solutions only
Short Questions – Chapter 10
1. Define a base and explain that all alkalies are bases, but all bases are not alkalies.
Answer:
A base is a substance that accepts protons (H⁺ ions) or produces hydroxide ions (OH⁻) in aqueous solution. Bases usually turn red litmus blue and show alkaline properties.
Alkalies are those bases that are soluble in water and produce OH⁻ ions in solution. For example, NaOH, KOH, and Ca(OH)₂ are alkalies because they dissolve in water and release hydroxide ions. However, some bases like Cu(OH)₂ and Fe(OH)₃ are insoluble in water, so they are bases but not alkalies.
Therefore, all alkalies are bases, but all bases are not alkalies.
2. Define Bronsted–Lowry base and explain with an example that water is a Bronsted–Lowry base.
Answer:
According to the Bronsted–Lowry concept, a base is a substance that accepts a proton (H⁺).
In the reaction:
NH₃ + H₂O ⇌ NH₄⁺ + OH⁻
NH₃ accepts a proton (H⁺), so it acts as a Bronsted–Lowry base, while H₂O donates a proton and behaves as a Bronsted–Lowry acid.
However, water can also act as a base in another reaction:
HCl + H₂O → H₃O⁺ + Cl⁻
In this reaction, H₂O accepts a proton (H⁺) from HCl and forms H₃O⁺. Therefore, water acts as a Bronsted–Lowry base. This shows that water is an amphoteric substance because it can act as both an acid and a base depending on the reaction.
3. Why does H⁺ ion act as a Lewis acid?
Answer:
-
The H⁺ ion (proton) has no electrons and can accept a lone pair of electrons from another substance.
-
According to the Lewis concept, acids are electron pair acceptors.
-
Therefore, H⁺ acts as a Lewis acid because it accepts electron pairs to form a coordinate bond.
Example Reaction:
H++H2O→H3O+H⁺ + H₂O → H₃O⁺
In this reaction, H⁺ accepts a lone pair of electrons from H₂O to form the hydronium ion (H₃O⁺).
Download PDF
English Medium View English Medium
Urdu Medium View Urdu Medium PDF