Free Acids, Bases and Salts MCQs with Answers

• A. electrolytes ionize in water to produce cations and anions
• B. ionization is a reversible process
• C. electrical conductivity of a solution of an electrolyte depends on the extent to which the electrolyte ionizes in the solution
• D. strong electrolyte ionize to a greater extent in water

Explanation: The Arrhenius theory of ionization does not specifically address the reversibility of the ionization process.

• A. NaCl
• B. Na2SO4
• C. Na2CO3
• D. FeCl3

Explanation: When dissolved in water, Na2CO3 undergoes hydrolysis, where water molecules react with the carbonate ion (CO3^2-) to produce hydroxide…

• A. Higher side
• B. Lower side
• C. Optimum side
• D. Constant

Explanation: At the start of a reaction, the concentration of reactants is on the higher side.

• A. HNO3
• B. H2SO4
• C. H2SO3
• D. H3PO4

Explanation: Sulfuric acid (H2SO4) is an acid that can act as an oxidizing, dehydrating, and acid-producing agent.Oxidizing agent: Sulfuric acid can…

• A. HCl
• B. H2S
• C. HBr
• D. H20

Explanation: HCl is a strong Bronsted acid because it readily donates a proton (H⁺ ion) when dissolved in water, forming the hydronium ion (H₃O⁺).

• A. NO₃⁻
• B. Cl⁻
• C. SO₄ ²⁻
• D. CH₃COO⁻

Explanation: The strength of a conjugate base is inversely related to the strength of its acid.

• A. Bronsted-Lowry base
• B. Bronsted-Lowry acid
• C. Lewis acid
• D. Lewis base

Explanation: According to the Brønsted-Lowry theory, a base is defined as a substance that can accept a proton (H⁺).

• A. CH₃COOH
• B. HCl
• C. HNO₃
• D. H₂SO₄

Explanation: There is an inverse relationship between the strength of an acid and its conjugate base. A weak acid will have a strong conjugate base.

• A. 6
• B. 13
• C. 11
• D. 12

Explanation: NaOH is a strong base, so [OH⁻] = 0.001 M = 10⁻³ M. The pOH is -log[OH⁻] = -log(10⁻³) = 3.

• A. CH₃COOH and (NH₄)₂SO₄
• B. NH₄NO₃ and KNO₃
• C. NH₄OH and NH₄Cl
• D. NH₄OH and NaCl

Explanation: A solution that maintains a constant pH is a buffer solution. A basic buffer is formed by mixing a weak base with the salt of that weak…

• A. SO₄ ²⁻
• B. H₃O⁺
• C. HSO₄⁻
• D. NH₄⁺

Explanation: A Bronsted-Lowry acid is a proton (H⁺) donor. The sulfate ion (SO₄²⁻) does not have any protons to donate, so it cannot function as a…

• A. CH₃-NH₂
• B. PH₃
• C. AlCl₃
• D. H₂O

Explanation: A Lewis base has a lone pair of electrons to donate. Aluminum chloride (AlCl₃) is electron-deficient as the central aluminum atom has an…

• A. The weaker the base
• B. The stronger the base
• C. The stronger the acid
• D. None of the above

Explanation: pKb is the negative logarithm of the base dissociation constant, K(-log Kb ).

• A. HCl(aq)
• B. HNO₃(aq)
• C. HF(aq)
• D. H₂SO₄(aq)

Explanation: pH is a measure of acidity; a higher pH means a weaker acid. Among the choices, hydrofluoric acid (HF) is the weakest acid.

• A. An electron pair
• B. a proton
• C. an electron
• D. a pair of protons

Explanation: A Lewis acid is defined as a substance that accepts an electron pair to form a coordinate bond. Since the question uses this definition.

• A. Red
• B. Yellow
• C. Orange
• D. Pink

Explanation: Methyl orange is an acid-base indicator that is red in acidic medium. In basic solution, it changes to its yellow form.

• A. Acid
• B. Salt
• C. Base
• D. Solvent

Explanation: An acidic buffer consists of a weak acid and its salt. The salt is a strong electrolyte that dissociates completely in solution, providing…

• A. NH₄NO₃
• B. NaCN
• C. NH₄NO₂
• D. K₂CO₃

Explanation: Ammonium nitrite (NH₄NO₂) is formed from the reaction of a weak base, ammonia (NH₃ or NH₄OH), and a weak acid, nitrous acid (HNO₂).

• A. CH₃COONa
• B. NaCN
• C. CuCl₂
• D. Na₂CO₃

Explanation: Copper(II) chloride (CuCl₂) is a salt of a weak base (Cu(OH)₂) and a strong acid (HCl).

• A. Acetic acid / sodium acetate
• B. Phosphoric acid / potassium dihydrogen phosphate
• C. Formic acid / sodium formate
• D. All of these

Explanation: An acidic buffer is a mixture of a weak acid and its conjugate base (usually from a salt).