Acid and Base MCQs

Set of Important MCQs on acid-base equilibrium for the preparation of test for chemistry and biology. 

Which is not Lewis base?

  1. NH3
  2. Pyridine
  3. H2O
  4. BF

Question’s Answer: BF


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

  1. Hemoglobin and bicarbonate buffers
  2. Hemoglobin and plasma proteins
  3. Bicarbonate and phosphate buffers
  4. Phosphate buffer and plasma proteins

Question’s Answer: Hemoglobin and bicarbonate buffers


Which concept is also called as proton-donor acceptor system?

  1. Usanovich
  2. Lewis
  3. Lux-Flood
  4. Bronsted-Lowery

Question’s Answer: Bronsted-Lowery


Which concept is also called as electron pair-donor acceptor system?

  1. Bronsted-Lowery
  2. Lewis
  3. Lux-Flood
  4. Usanovich

Question’s Answer: Lewis


The pKa of an acid is defined as

  1. The pH at which the acid starts dissociating
  2. Negative log of its ionization constant
  3. The pH at which all the ionizable residues are half dissociated
  4. None of these

Question’s Answer: Negative log of its ionization constant


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

  1. Boyle
  2. Liebig
  3. Davy
  4. Rouelle

Question’s Answer: Boyle


An acid is a substance that results in __.

  1. Accepts electrons from a donor
  2. Gives a hydronium ion
  3. Yields an hydride ion
  4. All of these

Question’s Answer: Gives a hydronium ion


Which is not a fixed acid?

  1. Citric acid
  2. Carbonic acid
  3. Phosphoric acid
  4. Lactic acid

Question’s Answer: Carbonic acid


Which acid-base conditions is characterized by primary carbonic acid excess?

  1. Respiratory alkalosis
  2. Metabolic
  3. Metabolic alkalosis acidosis
  4. Respiratory acidosis

Question’s Answer: Respiratory acidosis



According to which effect, All the strong acids have very close pKa value and they seem to have approximately equal strengths in aqueous solutions?

  1. Leveling effect
  2. Electrophoretic effect
  3. Debye effect
  4. Solvent effect

Question’s Answer: Leveling effect


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

  1. HI> HBr > HCl > HF
  2. HF> HCI > HBr >
  3. HCl > HBr > HI> HF
  4. HF> HI>HCI > Br

Question’s Answer: HI> HBr > HCl > HF


Relative order of acidity of oxy acids is:

  1. HCIO> HCIO2> HCIO3> HCIO4
  2. HCIO4> HCIO3> HCIO2> HCIO
  3. HCIO3>HCIO₂> HCIO> HCIO4
  4. HCIO2>HCIO4> HCIO3> HCIO

Question’s Answer: HCIO2>HCIO4> HCIO3> HCIO


pH of pure water at 25°C and Kw = 1 x 10

  1. 7
  2. 0
  3. 14
  4. None of these

Question’s Answer: 7


The ionic product equilibrium constant of water is

  1. Ka
  2. Kb
  3. Kw
  4. Kc

Question’s Answer: Kw


Which is not true with respect to buffers?

  1. They are made up of strong acid and weak base
  2. They are made up of weak base and its salt
  3. They tend to resist a change in pH value
  4. They are made up of weak acid and its salt

Question’s Answer: They are made up of strong acid and weak base


The value of Kw increases with temperature ______.

  1. Decreases because the ionization of water
  2. Increases
  3. Remains constant
  4. First decreases and then increases

Question’s Answer: Increases


The bicarbonate buffer system of our body has pK _______.

  1. 7.6
  2. 6.5
  3. 7.2
  4. 6.1

Question’s Answer: 6.1


What is the pH of the tears?

  1. 8.2
  2. 3.2
  3. 7.4
  4. 8.2

Question’s Answer: 7.4


What is the pH of milk?

  1. 6.5
  2. 6.0
  3. 7.0
  4. 7.5

Question’s Answer: 6.5


What is the pH of the 0.1 M HCl solution?

  1. 0.01
  2. 2.1
  3. 1
  4. 0.2

Question’s Answer: 1


What is the pH of the 1 M HCl?

  1. 1
  2. 2.1
  3. 0
  4. 1.3

Question’s Answer: 0


The sum of pH and pOH is equal to which of the following?

  1. 1
  2. 14
  3. 13
  4. 2

Question’s Answer: 14



Buffer solution are helpful and used to

  1. Resist the pH change
  2. Decrease the pH
  3. Increase the pH
  4. None of these

Question’s Answer: Resist the pH change


A mixture of weak acid and its salt is

  1. Acidic buffer
  2. Alkaline buffer
  3. Neutral buffer
  4. None of these

Question’s Answer: Acidic buffer


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

  1. Acetic acid
  2. Gelatin
  3. Ethyl alcohol
  4. All of these

Question’s Answer: All of these


The pH value 4.2 is of:

  1. Vinegar
  2. Tomatoes
  3. Oranges
  4. Lemons

Question’s Answer: Tomatoes


If the pH of solution is 1, its pOH will be

  1. 11
  2. 13
  3. 9
  4. 10

Question’s Answer: 13


Which is not Lowery-Bronsted acid?

  1. HCI
  2. Cl
  3. HS-
  4. H2O

Question’s Answer: Cl


Which is not Lowery-Bronsted Base?

  1. NH3
  2. H2O
  3. HCI
  4. HS

Question’s Answer: HCI


Which is not Lewis acid?

  1. Cl
  2. BF3
  3. AlCl3
  4. HCI

Question’s Answer: Cl



Which is not true with respect to strong acids?

  1. They have a pK value of less than 3
  2. Higher K value means strong acid
  3. They can have more than one pK
  4. Lowering the pH below their pK will cause their dissociation

Question’s Answer: Lowering the pH below their pK will cause their dissociation


Which amino acids is responsible for buffer action in blood?

  1. Pyridine
  2. Glutamine
  3. Histidine
  4. Glycine

Question’s Answer: Histidine


Which amino acids has S-S bond?

  1. Cistine
  2. Cisteine
  3. Glutamine
  4. Histidine

Question’s Answer: Cistine


Which buffers is not present in the blood?

  1. Carbonate-bicarbonate buffer
  2. Phosphate buffer
  3. Tris/ HCl buffer
  4. Protein buffer

Question’s Answer: Tris/ HCl buffer


Which is not true with respect to carbonate buffers?

  1. It is an open system
  2. The bicarbonate concentration is mainly qontrolled by lungs
  3. The dissolved CO2 is in equilibrium with the CO2 gas
  4. Bicarbonate is non-respiratory component of the buffer system

Question’s Answer: The bicarbonate concentration is mainly qontrolled by lungs


What is the approximate percentage of water in the body?

  1. 60%
  2. 50%
  3. 40%
  4. 70%

Question’s Answer: 60%


Which is the percentage of intracellular fluids in the body?

  1. 70%
  2. 50%
  3. 60%
  4. 40%

Question’s Answer: 40%


How much metabolic water is produced per 100 calories of energy produced in human body?

  1. 10-15 mL
  2. 1-5 mL
  3. 25-50 mL
  4. 50-100 mL

Question’s Answer: 10-15 mL


Which results in generation of highest amount of metabolic water (per gram oxidation of the substance)?

  1. Carbohydrates
  2. Proteins
  3. Fats
  4. Nucleic acids

Question’s Answer: Fats


Which has higher concentration in the extracellular compartment than the intracellular?

  1. Magnesium
  2. Phosphate
  3. Sulphate
  4. Bicarbonate

Question’s Answer: Bicarbonate


Which does not contribute to the osmolality?

  1. Urea
  2. Proteins
  3. Sodium
  4. Pyric acid

Question’s Answer: Urea


Which of the following happens due to Donnan effect?

  1. Concentartion of the anions is higher in the interstitial fluids
  2. Concentartion of the catios is higher in the interstitial fluids
  3. Proteins bind chloride at physiological pH
  4. Sodium and potassium laek out of plasma

Question’s Answer: Concentartion of the anions is higher in the interstitial fluids


Which is minimum?

  1. Metabolic water
  2. Water lost in sweat
  3. Water in food
  4. Daily urinary output

Question’s Answer: Water lost in sweat


What is the pH of the blood?

  1. 4.3
  2. 8.2
  3. 6.1
  4. 7.4

Question’s Answer: 7.4


Which is not true with respect to pKa value?

  1. The stronger the acid, the smaller its pKa value
  2. The stronger the acid, the larger its pKa value
  3. The stronger the base, the larger its pKa value
  4. The pKa value can be determined experimentally

Question’s Answer: The stronger the acid, the larger its pKa value


Which aqueous solution has low pH value?

  1. 0.1 M acetic acid
  2. 0.1 M hydrochloric acid
  3. 0.1 M formic acid
  4. 0.1 M phosphoric acid

Question’s Answer: 0.1 M hydrochloric acid


Which mixture does not act as buffers?

  1. Acetic acid/sodium acetate
  2. Phosphoric acid/sodium phospahte
  3. Trisbase/HCl
  4. Sodium chloride/hydrochloric acid

Question’s Answer: Sodium chloride/hydrochloric acid


Which statement is not true about amino acid glycine?

  1. It is a main ingredient of buffers helpful and used in biochemical experiments
  2. The amino group of glycine has a pKa value 4.74
  3. The amino group can exist in protonated form
  4. The amino group can exist in free form

Question’s Answer: The amino group of glycine has a pKa value 4.74


Which combinations is helpful and used to prepare buffers of pH 7.0?

  1. Acetic acid/sodium acetate
  2. Sodium borate/boric acid
  3. Phosphoric acid/sodium phosphate
  4. Tribase/HCl

Question’s Answer: Phosphoric acid/sodium phosphate


The pH of human stomach is

  1. 6.0 to 7.0
  2. 4.0 to 6.0
  3. 1.5 to 2.5
  4. None of these

Question’s Answer: 1.5 to 2.5


Which biochemical reactions involve water as reactant?

  1. Hydrolysis
  2. Condensation
  3. Redox
  4. All of these

Question’s Answer: All of these


What is the optimum range for best working of acetate buffer?

  1. 1.76-4.76
  2. 2.76-3.76
  3. 3.76-5.76

D 4.76-7.76

Question’s Answer: 3.76-5.76


In water at 25°C, the concentration of water is ______.

  1. 54.5 M
  2. 55.5 M
  3. 53.5 M
  4. 52.5 M

Question’s Answer: 55.5 M


Which properties of water is not associated with H-bonding?

  1. Higher M.P.
  2. Higher B.P.
  3. High density
  4. Heat of vaporization

Question’s Answer: High density


Which bond is weak?

  1. H-bond
  2. Ionic bond
  3. Covalent bond
  4. Metallic bond

Question’s Answer: H-bond


Which is not true with respect to hemoglobin?

  1. hemoglobin can bind CO2 to form carboxyhemoglobin
  2. hemoglobin acts as buffer because carboxyhemoglobin is a strong acid
  3. The deoxyhemoglobin in tissues is bound to proton
  4. In RBC, the formation of carbonic acid is facilitated by carbonic anhydrase

Question’s Answer: It acts as buffer because carboxyhemoglobin is a strong acid


Amphipathic compounds are substances that contain regions

  1. Non-polar regions
  2. Polar regions
  3. Both polar and non-polar
  4. None of these

Question’s Answer: Both polar and non-polar


The forces that hold the non-polar regions of the molecules together are referred as

  1. H-bonding
  2. Hydrophobic interactions
  3. Dipole interactions
  4. van der Waals forces

Question’s Answer: Hydrophobic interactions


Which biomolecules are amphipathic?

  1. Proteins
  2. Phospholipids
  3. Pigments
  4. All of these

Question’s Answer: All of these


Solutes of all kinds alter certain physical properties of water (vapor pressure, B.P. osmotic pressure). These are called

  1. Colligative properties
  2. Additive properties
  3. Chemical properties
  4. Constitutive properties

Question’s Answer: Colligative properties



The pH at which the dipolar ion does not migrate in an electric field is called

  1. Isobestic point
  2. Critical point
  3. Neutral point
  4. Isoelectric point

Question’s Answer: Isoelectric point


The isoelectric point of glycine amino acid is

  1. 3.98
  2. 1.98
  3. 2.98
  4. 4.98

Question’s Answer: 2.98


Solutions of osmolarity equal to that of cells cytosol are said to be

  1. Hypertoinc
  2. Hypotonic
  3. Isotonic
  4. None of these

Question’s Answer: Isotonic


Solutions of osmolarity higher to that of cell,s cytosol are said to be

  1. Hypotonic
  2. Isotonic
  3. Hypertoinc
  4. None of these

Question’s Answer: Hypertoinc


Solutions of osmolarity lower to that of cells cytosol are said to be

  1. Hypotonic
  2. Isotonic
  3. Hypertoinc
  4. None of these

Question’s Answer: Hypotonic


Which acids is polyprotic acid?

  1. Sulfuric acid
  2. Phosphoric acid
  3. Carbonic acid
  4. All of these

Question’s Answer: All of these


Which amino acids is not optically active?

  1. Histidine
  2. Alanine
  3. Glycine
  4. Glutamine

Question’s Answer: Glycine


Which amino acids has L- configuration?

  1. Glutamine
  2. Alanine
  3. Histidine
  4. All of these

Question’s Answer: All of these



Which amino acids contains imidazole ring?

  1. Pyridine
  2. Glycine
  3. Glutamine
  4. Histidine

Question’s Answer: Histidine


Which is a biological buffer(s)?

  1. MES monohydrate.
  2. MOPS
  3. HEPES
  4. All of these

Question’s Answer: All of these


Which amino acids have two carboxylic groups?

  1. Glutamine
  2. Histidine
  3. Aspartic acid
  4. Glycine

Question’s Answer: Aspartic acid


Which amino acids have two amino groups?

  1. Aspartic acid
  2. Isoleucine
  3. Glycine
  4. Asparagine

Question’s Answer: Asparagine


When two charged atoms are brought together, their surrounding electron clouds influence each other and create transient electric dipoles which attract each other. These weak attractions are called –

  1. H-bonding
  2. van der Waals interactions
  3. Dipole interactions
  4. Hydrophobic interactions

Question’s Answer: van der Waals interactions


Lewis concept explain the formation of

  1. Co-ordinate bond
  2. Covalent bond
  3. Ionic bond
  4. Hydrogen bond

Question’s Answer: Co-ordinate bond


The pK of an acid ______.

  1. Is an indicator of the strength of the buffer
  2. Signifies the buffering capacity of the buffer solution
  3. Reflects the pH of a solution

D: All of these

Question’s Answer: All of these

Water movement across a semi-permeable membrane driven by osmotic pressure difference is called

  1. Diffusion
  2. Osmosis
  3. Donann equilibrium
  4. None of these

Question’s Answer: Osmosis

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

Prof.Fazal Rehman Shamil (Available for Professional Discussions)
1. Message on Facebook page for discussions,
2. Video lectures on Youtube
3. Email is only for Advertisement/business enquiries.