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Acid and Base MCQs

1. : Which is not a Lewis base?

(A) NH3


(B) Pyridine


(C) H2O


(D) BF3



2. : The difference in the pH of arterial and venous blood is very minor because of the interaction between:

(A) Hemoglobin and bicarbonate buffers


(B) Hemoglobin and plasma proteins


(C) Bicarbonate and phosphate buffers


(D) Phosphate buffer and plasma proteins



3. : Which concept is also called a proton-donor acceptor system?

(A) Usanovich


(B) Lewis


(C) Lux-Flood


(D) Bronsted-Lowery



4. : Which concept is also called an electron pair-donor acceptor system?

(A) Bronsted-Lowery


(B) Lewis


(C) Lux-Flood


(D) Usanovich



5. : The pKa of an acid is defined as

(A) The pH at which the acid starts dissociating


(B) Negative log of its ionization constant


(C) The pH at which all the ionizable residues are half dissociated


(D) None of these



6. : According to ______, “Acids are substances whose aqueous solutions turned blue litmus red and tasted sour.”

(A) Boyle


(B) Liebig


(C) Davy


(D) Rouelle



7. : An acid is a substance that results in __.

(A) Accepts electrons from a donor


(B) Gives a hydronium ion


(C) Yields a hydride ion


(D) All of these



8. : Which is not a fixed acid?

(A) Citric acid


(B) Carbonic acid


(C) Phosphoric acid


(D) Lactic acid



9. : Which acid-base condition is characterized by primary carbonic acid excess?

(A) Respiratory alkalosis


(B) Metabolic acidosis


(C) Metabolic alkalosis


(D) Respiratory acidosis



10. : According to which effect, all the strong acids have very close pKa values and they seem to have approximately equal strengths in aqueous solutions?

(A) Leveling effect


(B) Electrophoretic effect


(C) Debye effect


(D) Solvent effect



11. : Relative order of acidity of HF, HCl, HBr and HI acids is:

HBr > HCl > HF” onclick=”checkAnswer(‘q11’, ‘HI > HBr > HCl > HF’)”> (A) HI > HBr > HCl > HF


HCl > HBr > HI” onclick=”checkAnswer(‘q11’, ‘HI > HBr > HCl > HF’)”> (B) HF > HCl > HBr > HI


HBr > HI > HF” onclick=”checkAnswer(‘q11’, ‘HI > HBr > HCl > HF’)”> (C) HCl > HBr > HI > HF


HI > HCl > Br” onclick=”checkAnswer(‘q11’, ‘HI > HBr > HCl > HF’)”> (D) HF > HI > HCl > Br



12. : Relative order of acidity of oxy acids is:

HClO2 > HClO3 > HClO4″ onclick=”checkAnswer(‘q12’, ‘HClO2 > HClO4 > HClO3 > HClO’)”> (A) HClO > HClO2 > HClO3 > HClO4


HClO3 > HClO2 > HClO” onclick=”checkAnswer(‘q12’, ‘HClO2 > HClO4 > HClO3 > HClO’)”> (B) HClO4 > HClO3 > HClO2 > HClO


HClO2 > HClO > HClO4″ onclick=”checkAnswer(‘q12’, ‘HClO2 > HClO4 > HClO3 > HClO’)”> (C) HClO3 > HClO2 > HClO > HClO4


HClO4 > HClO3 > HClO” onclick=”checkAnswer(‘q12’, ‘HClO2 > HClO4 > HClO3 > HClO’)”> (D) HClO2 > HClO4 > HClO3 > HClO



13. : pH of pure water at 25°C (Kw = 1 x 10⁻¹⁴) is:

(A) 7


(B) 0


(C) 14


(D) None of these



14. : The ionic product equilibrium constant of water is:

(A) Ka


(B) Kb


(C) Kw


(D) Kc



15. : Which is not true with respect to buffers?

(A) They are made up of strong acid and weak base


(B) They are made up of weak base and its salt


(C) They tend to resist a change in pH value


(D) They are made up of weak acid and its salt



16. : The value of Kw increases with temperature ______.

(A) Decreases because the ionization of water


(B) Increases


(C) Remains constant


(D) First decreases and then increases



17. : The bicarbonate buffer system of our body has pK _______.

(A) 7.6


(B) 6.5


(C) 7.2


(D) 6.1



18. : What is the pH of tears?

(A) 8.2


(B) 3.2


(C) 7.4


(D) 8.2



19. : What is the pH of milk?

(A) 6.5


(B) 6.0


(C) 7.0


(D) 7.5



20. : What is the pH of the 0.1 M HCl solution?

(A) 0.01


(B) 2.1


(C) 1


(D) 0.2



21. : What is the pH of 1 M HCl?

(A) 1


(B) 2.1


(C) 0


(D) 1.3



22. : The sum of pH and pOH is equal to:

(A) 1


(B) 14


(C) 13


(D) 2



23. : Buffer solutions are helpful and used to:

(A) Resist the pH change


(B) Decrease the pH


(C) Increase the pH


(D) None of these



24. : A mixture of weak acid and its salt is called:

(A) Acidic buffer


(B) Alkaline buffer


(C) Neutral buffer


(D) None of these



25. : Glass electrode cannot be helpful and used to measure the pH of pure:

(A) Acetic acid


(B) Gelatin


(C) Ethyl alcohol


(D) All of these



26. : The pH value 4.2 is typical of:

(A) Vinegar


(B) Tomatoes


(C) Oranges


(D) Lemons



27. : If the pH of a solution is 1, its pOH will be:

(A) 11


(B) 13


(C) 9


(D) 10



28. : Which is not a Lowery-Bronsted acid?

(A) HCl


(B) Cl⁻


(C) HS⁻


(D) H2O



29. : Which is not a Lowery-Bronsted base?

(A) NH3


(B) H2O


(C) HCl


(D) HS⁻



30. : Which is not a Lewis acid?

(A) Cl⁻


(B) BF3


(C) AlCl3


(D) HCl



31. : Which is not true with respect to strong acids?

(A) They have a pK value of less than 3


(B) Higher K value means strong acid


(C) They can have more than one pK


(D) Lowering the pH below their pK will cause their dissociation



32. : Which amino acid is responsible for buffer action in blood?

(A) Pyridine


(B) Glutamine


(C) Histidine


(D) Glycine



33. : Which amino acid has S-S bond?

(A) Cistine


(B) Cisteine


(C) Glutamine


(D) Histidine



34. : Which buffer is not present in the blood?

(A) Carbonate-bicarbonate buffer


(B) Phosphate buffer


(C) Tris/HCl buffer


(D) Protein buffer



35. : Which is not true with respect to carbonate buffers?

(A) It is an open system


(B) The bicarbonate concentration is mainly controlled by lungs


(C) The dissolved CO2 is in equilibrium with the CO2 gas


(D) Bicarbonate is a non-respiratory component of the buffer system



36. : What is the approximate percentage of water in the human body?

(A) 60%


(B) 50%


(C) 40%


(D) 70%



37. : What is the percentage of intracellular fluids in the body?

(A) 70%


(B) 50%


(C) 60%


(D) 40%



38. : How much metabolic water is produced per 100 calories of energy in the human body?

(A) 10-15 mL


(B) 1-5 mL


(C) 25-50 mL


(D) 50-100 mL



39. : Which macronutrient results in the highest amount of metabolic water (per gram oxidation)?

(A) Carbohydrates


(B) Proteins


(C) Fats


(D) Nucleic acids



40. : Which ion has a higher concentration in the extracellular compartment than intracellular?

(A) Magnesium


(B) Phosphate


(C) Sulphate


(D) Bicarbonate



41. : Which does not contribute to the osmolality?

(A) Urea


(B) Proteins


(C) Sodium


(D) Pyric acid



42. : Which of the following happens due to the Donnan effect?

(A) Concentration of the anions is higher in the interstitial fluids


(B) Concentration of the cations is higher in the interstitial fluids


(C) Proteins bind chloride at physiological pH


(D) Sodium and potassium leak out of plasma



43. : Which is minimum?

(A) Metabolic water


(B) Water lost in sweat


(C) Water in food


(D) Daily urinary output



44. : What is the pH of blood?

(A) 4.3


(B) 8.2


(C) 6.1


(D) 7.4



45. : Which is not true with respect to pKa value?

(A) The stronger the acid, the smaller its pKa value


(B) The stronger the acid, the larger its pKa value


(C) The stronger the base, the larger its pKa value


(D) The pKa value can be determined experimentally



46. : Which aqueous solution has the lowest pH value?

(A) 0.1 M acetic acid


(B) 0.1 M hydrochloric acid


(C) 0.1 M formic acid


(D) 0.1 M phosphoric acid



47. : Which mixture does not act as a buffer?

(A) Acetic acid/sodium acetate


(B) Phosphoric acid/sodium phosphate


(C) Tris base/HCl


(D) Sodium chloride/hydrochloric acid



48. : Which statement is not true about amino acid glycine?

(A) It is a main ingredient of buffers used in biochemical experiments


(B) The amino group of glycine has a pKa value of 4.74


(C) The amino group can exist in protonated form


(D) The amino group can exist in free form



49. : Which combinations are helpful to prepare buffers of pH 7.0?

(A) Acetic acid/sodium acetate


(B) Sodium borate/boric acid


(C) Phosphoric acid/sodium phosphate


(D) Tris base/HCl



50. : The pH of the human stomach is?

(A) 6.0 to 7.0


(B) 4.0 to 6.0


(C) 1.5 to 2.5


(D) None of these



More Biochemistry MCQs

  1. Acid and Base MCQs
  2. Carbohydrate MCQs
  3. Proteins MCQs
  4. Lipids and Biomembranes MCQs
  5. Nucleic acids MCQs
  6. Metabolism of Carbohydrates MCQs
  7. Enzymes MCQs
  8. Vitamins and Hormones MCQs
  9. Bioenergetic MCQs
  10. Biotechnology MCQs
  11. Biotechnology MCQs 2
  12. Basic Biochemistry MCQs (important)
  13. CHEMISTRY MCQs From all subjects of  Chemistry

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