Free Buffer Solutions MCQs with Answers

• A. has a pH of exactly 7
• B. neutralises all acids completely
• C. resists a change in pH when a small amount of acid or base is added
• D. conducts electricity better than water

Explanation: A buffer contains a reservoir of both a weak acid and its conjugate base, so added hydrogen ions are mopped up by the base and added…

• A. Hydrochloric acid and sodium chloride
• B. Sodium hydroxide and sodium chloride
• C. Ammonia and ammonium chloride
• D. Acetic acid and sodium acetate

Explanation: An acidic buffer needs a weak acid together with the salt of that acid, and acetic acid with sodium acetate is the standard example.

• A. the total volume of the solution
• B. the temperature only
• C. the presence of a catalyst
• D. the dissociation constant of the acid and the ratio of salt to acid concentration

Explanation: The Henderson Hasselbalch relationship gives pH as pKa plus the logarithm of the ratio of salt to acid, so it is the ratio that matters…

• A. NH4OH/NH4Cl
• B. NaOH/NaCl
• C. NaOH/HCl
• D. H2CO3/NaHCO3

Explanation: A basic buffer needs a weak base together with the salt of that base, and ammonium hydroxide with ammonium chloride is the standard…

• A. More ammonium hydroxide is formed
• B. Reaction will move reverse
• C. Reaction will move forward
• D. No effect on equilibrium

Explanation: The added hydrogen ions are mopped up by the weak base ammonium hydroxide, which reacts forward to give ammonium ions and water, so the pH…

• A. Neutralization
• B. Osmosis
• C. Buffer
• D. Active transport

Explanation: A buffer resists a change in pH when small amounts of acid or base are added because its weak acid and conjugate base, or weak base and…

• A. 8 to 14
• B. 6 to 10
• C. 7 to 11
• D. 0 to 14

Explanation: On the usual 0 to 14 pH scale, alkaline solutions have pH values greater than 7, commonly written as 8 to 14.

• A. 9 to 8
• B. 6 to 7
• C. 1 to 6
• D. 1 to 10

Explanation: On the school-level pH scale, acids have pH values below 7, commonly represented as 1 to 6.

• A. 5
• B. 3
• C. 7
• D. 10

Explanation: A pH of 7 is neutral at about 25 °C because the concentrations of hydrogen ions and hydroxide ions are equal.

• A. methyl Orange
• B. litmus
• C. phenol red
• D. phenopthalein

Explanation: HCl is a strong acid and NH4OH is a weak base, so their equivalence point is acidic because NH4+ hydrolyses to produce H3O+.

• A. H2CO3 - HCO3
• B. H2CO3 - CO32-
• C. CH3COOH - CH3COO-
• D. NH2CONH2 - NH2CONH+

Explanation: The principal blood buffer is the carbonic acid-bicarbonate pair, H2CO3 and HCO3-.

• A. 0.115
• B. 0.900
• C. 0.015
• D. 0.215

Explanation: Buffer capacity can be estimated as the amount of strong base added per unit change in pH: β = 0.010 mol / (4.832 - 4.745) = 0.010 mol /…

• A. 7.0
• B. 7.4
• C. 7.8
• D. 8.2

Explanation: Tears are maintained close to neutral but are usually slightly alkaline, with a pH of about 7.4.

• A. Very strong base
• B. Very weak acid
• C. Very strong acid
• D. Very strong salt

Explanation: A small Ka indicates that an acid ionises only slightly in water, so Ka less than 10^-3 is intended here to indicate a weak acid.

• A. Gibbs
• B. Einstein
• C. Sorenson
• D. Chadwick

Explanation: Sørensen introduced the pH scale in 1909 and the related pOH concept is treated with it in acid-base chemistry.

• A. 0.0002M HCI
• B. 0.2 mole of NaCI with 0.2 mole of HNO3
• C. 0.4 mole of CH3COOH with 0.4 mole of NaOH
• D. 0.4 mole of NH3 with 0.2 mole of HCI

Explanation: A buffer contains a weak base and its conjugate acid. HCl neutralizes half of the 0.4 mol NH3, leaving 0.2 mol NH3 and producing 0.2 mol…

• A. KOH
• B. NH3
• C. PH3
• D. BF3

Explanation: BF3 is a Lewis acid because the boron atom accepts an electron pair, so it is not a base.

• A. 0
• B. 1
• C. 2
• D. any one

Explanation: For a buffer, pH = pKa + log([benzoate]/[benzoic acid]). Equimolar amounts give [benzoate]/[benzoic acid] = 1, and log 1 = 0, so pH = 2 +…

• A. buffer solution
• B. normal solution
• C. standard solution
• D. neutral solution

Explanation: A buffer contains a weak acid and its conjugate base, or a weak base and its conjugate acid, so it consumes small added amounts of H+ or…

• A. brine
• B. blood
• C. glue
• D. solution of CuSO4

Explanation: Blood contains the carbonic acid-hydrogen carbonate buffer system, which helps maintain blood pH despite small additions of acid or base.