Free Acids, Bases and Salts MCQs with Answers

• A. Blood & egg (white)
• B. Tears & blood
• C. Tears & milk
• D. Milk & egg (white)

Explanation: Both human blood and tears are natural buffer systems that maintain a tightly controlled, slightly alkaline pH.

• A. HF & NaF
• B. NH₃ & NH₄Cl
• C. H₂CO₃ & NaHCO₃
• D. All of these

Explanation: A buffer solution consists of a weak acid and its conjugate base, or a weak base and its conjugate acid.

• A. Aniline
• B. Pyridine
• C. Ammonia
• D. Methylamine

Explanation: Aniline is the weakest base because the lone pair of electrons on its nitrogen atom is delocalized into the benzene ring through…

• A. 1.0×10⁻¹⁴
• B. 2.9×10⁻¹⁴
• C. 3.8×10⁻¹⁴
• D. 1.8×10⁻¹⁴

Explanation: The autoionization of water is an endothermic process. According to Le Chatelier's principle, increasing the temperature will shift the…

• A. Oxonium ion
• B. Hydroxonium ion
• C. Hydronium ion
• D. Hydroxyl ion

Explanation: In aqueous solutions, a free proton (H⁺) does not exist on its own. It is strongly attracted to the lone pairs of a water molecule…

• A. Milk
• B. Grape
• C. Apple
• D. Lemon

Explanation: Malic acid is a naturally occurring organic acid that is responsible for the sour taste of many fruits.

• A. KI
• B. CH₃COONH₄
• C. FeCl₃
• D. None

Explanation: "Ferric chloride (FeCl₃) is the salt of a weak base (Fe(OH)₃) and a strong acid (HCl).

• A. NaCl
• B. AlCl₃
• C. Na₂CO₃
• D. CH₃COONa

Explanation: NaCl is formed from a strong acid (HCl) and a strong base (NaOH), so its ions are too weak to react with water.

• A. CH₃COONa
• B. KNO₂
• C. NH₄NO₃
• D. NaI

Explanation: Ammonium nitrate (NH₄NO₃) is the salt of a weak base (NH₃) and a strong acid (HNO₃).

• A. KCl
• B. KNO₃
• C. CH₃COONH₄
• D. CH₃COONa

Explanation: Ammonium acetate (CH₃COONH₄) is formed from a weak acid, acetic acid (CH₃COOH), and a weak base, ammonia (NH₃).

• A. Basic
• B. Acidic
• C. Neutral
• D. Not predictable

Explanation: Sodium sulfate (Na₂SO₄) is a salt formed from a strong acid (H₂SO₄) and a strong base (NaOH).

• A. KAl(SO₄)₂
• B. Na₂CO₃
• C. Ca(OCl)Cl
• D. NaCl

Explanation: A mixed salt is a salt that contains more than one type of cation or anion.

• A. Acidic
• B. Basic
• C. Neutral
• D. Amphoteric

Explanation: Sodium phosphate is the salt of a strong base (NaOH) and a weak acid (HPO₄²⁻).

• A. Protogenic solvent
• B. Protophilic solvent
• C. Aprotic solvent
• D. Organic solvent

Explanation: A protogenic (acidic) solvent can differentiate the strengths of strong bases.

• A. pH = pKb + Log([Salt]/[Acid])
• B. pH = pKa + Log([Salt]/[Acid])
• C. pH = pKb + Log([Acid]/[Salt])
• D. pH = pKa + Log([Acid]/[Salt])

Explanation: This is the correct form of the Henderson-Hasselbalch equation used for calculating the pH of an acidic buffer.

• A. Leveling effect
• B. Solvent effect
• C. Le Chatelier's principle
• D. None of these

Explanation: The action of a buffer is an excellent example of Le Chatelier's principle.

• A. 4 moles of NH₃ with 2 moles of HCl
• B. 0.0002 mole of HCl
• C. 2 moles of NaCl with 2 moles of HCl
• D. 4 moles of CH₃COOH with 4 moles of NaCl

Explanation: NH₃ is a weak base, and partial neutralization with HCl produces NH₄⁺ (its conjugate acid).

• A. HNO₂ and NaNO₂
• B. HCN and NaCN
• C. NH₃ and (NH₄)₂SO₄
• D. All of these

Explanation: All of the options represent a mixture of a weak acid with its conjugate base (A and B) or a weak base with its conjugate acid (C).

• A. CaO
• B. CO₂
• C. SiO₂
• D. SnO₂

Explanation: Amphoteric oxides react with both acids and bases. Among the options, SnO₂ (tin oxide) shows this dual behavior.

• A. NH₄Cl
• B. NaCl
• C. CH₃COONa
• D. NaNO₃

Explanation: Sodium acetate (CH₃COONa) is the salt of a weak acid (CH₃COOH) and a strong base (NaOH).