32 + Interview Questions in Water Basics in Biochemistry Page 1 InterviewSolution

1.	If pKb for fluoride at 25°c is 10.83, the ionization constant of hydrofluoric acid in water at this temperature is?(a) 3.52×10^-3(b) 6.75×10^-4(c) 5.38×10^-2(d) 1.74×10^-5The question was asked in an international level competition.Query is from Ionization of Water, Weak acids and Weak Bases in chapter Water Basics of Biochemistry
Answer» The correct ANSWER is (b) 6.75×10^-4 To explain: KW = KA × Kb Ka = Kw / Kb Ka = 10^-14/-log (10.83) = 6.75 × 10^-4.

Discussion

2.	What makes water a liquid at room temperature?(a) Hydrogen bonds between water molecules(b) Covalent bonding(c) Noncovalent interactions(d) Van der Waals forces of attractionI had been asked this question in examination.This intriguing question originated from Weak Interactions in Aqueous Systems in division Water Basics of Biochemistry
Answer» Correct CHOICE is (a) HYDROGEN BONDS between water MOLECULES Easy explanation: Hydrogen bonds between water molecules provide the cohesive forces that make water a liquid at ROOM temperature.

Discussion

3.	Which of the following is a hypotonic solution?(a) 10% dextrose in water(b) 0.45% sodium chloride(c) 5% dextrose in 0.9% sodium chloride(d) OceansThis question was addressed to me during an interview for a job.Enquiry is from Weak Interactions in Aqueous Systems topic in division Water Basics of Biochemistry
Answer» The correct ANSWER is (b) 0.45% SODIUM chloride For EXPLANATION I would say: 0.9% NORMAL saline is isotonic and half of 0.9 = 0.45% makes the solution more diluted (contains more water), THEREFORE the solution is hypotonic.

Discussion

4.	Which of the following mixture in aqueous solution of equimolar concentration acts as a buffer solution?(a) HNO3 + NaOH(b) H2 SO4 + KOH(c) NH4 OH(excess) + HCl(d) CH3 COOH + NaOH(excess)I have been asked this question in class test.My question is taken from Buffering against pH changes in Biological Systems in section Water Basics of Biochemistry
Answer» The CORRECT answer is (C) NH4 OH(excess) + HCl The EXPLANATION is: NH4 OH(excess) + HCl → NH4 Cl + H2O So the MIXTURE contains NH4 OH + NH4 Cl.

Discussion

5.	Which of the following is an isotonic solution?(a) 0.9% sodium chloride(b) 0.45% sodium chloride(c) Oceans(d) 10% dextrose in waterI had been asked this question during an interview.The question is from Weak Interactions in Aqueous Systems topic in portion Water Basics of Biochemistry
Answer» The CORRECT choice is (a) 0.9% sodium chloride Easiest explanation: The NORMAL SALINE solution, 0.9% NaCl has the same salt CONCENTRATION as the surrounding BLOOD cells.

Discussion

6.	Buffer capacity is maximum when __________(a) One mole of NH4Cl is added to two moles of NH4OH(b) One mole of NH4Cl is added to one moles of NH4OH(c) One mole of NH4Cl is added to one mole of NaOH(d) One mole of NaCl is added to one mole of NaOHThis question was addressed to me during an online exam.My question is from Buffering against pH changes in Biological Systems in chapter Water Basics of Biochemistry
Answer» Right CHOICE is (b) ONE mole of NH4Cl is ADDED to one moles of NH4OH For EXPLANATION: Buffer has more capacity when pH = pKa.

Discussion

7.	The buffer capacity is equal to __________(a) Δn / ΔpH(b) pH / Δn(c) ± 1pKa(d) ± 2pKaThe question was posed to me during an online exam.My doubt stems from Buffering against pH changes in Biological Systems topic in portion Water Basics of Biochemistry
Answer» Correct ANSWER is (a) Δn / ΔpH Easiest explanation: Buffer capacity = NUMBER of moles of ACID or base added to 1 LITER of buffer/change in pH.

Discussion

8.	The bond dissociation energy of O-H bond in a water molecule is _____________(a) 23 kJ/mole(b) 470 kJ/mole(c) 470 J/mole(d) 23 J/moleThis question was posed to me by my school teacher while I was bunking the class.Asked question is from Weak Interactions in Aqueous Systems topic in portion Water Basics of Biochemistry
Answer» RIGHT answer is (B) 470 kJ/mole Best explanation: The energy REQUIRED to BREAK O-H bond in a water molecule is more than that required for breaking hydrogen bond, which is 470 kJ/mole.

Discussion

9.	Calculate the ratio of the concentrations of acetate and acetic acid required in a buffer system of pH 5.30.(a) 3.2(b) 3.3(c) 3.4(d) 3.5I have been asked this question during an interview.This interesting question is from Buffering against pH changes in Biological Systems topic in chapter Water Basics of Biochemistry
Answer» The correct choice is (d) 3.5 For explanation: PH = PKA + LOG [acetate]/[acetic ACID] log [acetate]/[acetic acid] = pH – pKa = 5.30 – 4.76 = 0.54 [acetate]/[acetic acid] = ANTILOG 0.54 = 3.5.

Discussion

10.	What is the factor that is responsible for salts like NaCl to dissolve in water easily?(a) Decrease in entropy(b) Increase in entropy(c) Increase in enthalpy(d) Decrease in enthalpyThe question was posed to me in quiz.My question is based upon Weak Interactions in Aqueous Systems topic in portion Water Basics of Biochemistry
Answer» Right choice is (b) Increase in entropy Easy EXPLANATION: As a salt such as NaCl dissolves, the Na^+ and Cl^– IONS leaves the crystal LATTICE RESULTING in an increase in entropy(randomness) of the SYSTEM which is largely responsible for the ease of dissolving salts such as NaCl in water.

Discussion

11.	The bond dissociation energy of hydrogen bonds in a water molecule is ______________(a) 470 kJ/mole(b) 470 J/mole(c) 23 kJ/mole(d) 23 J/moleI got this question in class test.This is a very interesting question from Weak Interactions in Aqueous Systems in portion Water Basics of Biochemistry
Answer» The CORRECT ANSWER is (c) 23 kJ/mole The explanation is: The energy REQUIRED to BREAK the HYDROGEN bonds (H-H) in water molecule is 23 kJ/mole.

Discussion

12.	Which of the following does not react with water?(a) Barium(b) Calcium(c) Beryllium(d) StrontiumI have been asked this question by my school principal while I was bunking the class.Asked question is from Water as a Reactant topic in division Water Basics of Biochemistry
Answer» The correct answer is (c) Beryllium To ELABORATE: Be is the only ALKALINE EARTH METAL which does not REACT with water.

Discussion

13.	The hydrolysis constant of CH3COONa is given by ____________(a) Kh = Kw/Ka(b) Kh = Kw/Kb(c) Kh = Kw/Ka×Kb(d) Kh =Ka +KbI got this question during an interview.This intriguing question comes from Ionization of Water, Weak acids and Weak Bases in chapter Water Basics of Biochemistry
Answer» RIGHT answer is (a) KH = Kw/Ka To elaborate: CH3COONA is a salt of WEAK ACID and strong base.

Discussion

14.	For an acid buffer solution the pH is 3. The pH can be increased by ____________(a) Increasing the concentration of salt(b) Increasing the concentration of acid(c) Decreasing the concentration of salt(d) Independent of concentration of acid & saltThis question was posed to me during an online exam.Asked question is from Buffering against pH changes in Biological Systems in division Water Basics of Biochemistry
Answer» The correct option is (a) Increasing the concentration of salt The EXPLANATION: An ACID buffer is a mixture of WEAK acid and its salt with strong BASE, its pH increases by increasing the concentration of salt.

Discussion

15.	Aqueous solution of the detergents are _________(a) Neutral(b) Acidic(c) Basic(d) AmphotericI had been asked this question during an interview.I need to ask this question from Ionization of Water, Weak acids and Weak Bases topic in division Water Basics of Biochemistry
Answer» The correct choice is (c) Basic The BEST I can EXPLAIN: Detergent is a salt of weak acid and STRONG BASE.

Discussion

16.	Which of the following is the correct equation?(a) CO2 + H2O H2CO3(b) CO2 + H2O HCO3(c) CO2 + H2O H3CO3(d) CO2 + H2O H2CO2This question was posed to me in unit test.This intriguing question originated from Water as a Reactant in division Water Basics of Biochemistry
Answer» RIGHT choice is (a) CO2 + H2O H2CO3 To ELABORATE: The correct balanced equation is CO2+ H2O H2CO3. CARBONDIOXIDE reacts with water to give CARBONIC acid.

Discussion

17.	What is the heat of vaporization of water?(a) 2260 J/g(b) 2260 kJ/g(c) 1260 J/g(d) 1260 kJ/gI got this question by my school teacher while I was bunking the class.Query is from Weak Interactions in Aqueous Systems in section Water Basics of Biochemistry
Answer» Right option is (a) 2260 J/g To elaborate: The amount of ENERGY needed to change one gram of water to its vapor FORM at CONSTANT TEMPERATURE is 2260 J/g.

Discussion

18.	Hydrolysis reactions are catalyzed by enzymes called ___________(a) Oxidoreductase(b) Ligase(c) Hydrolase(d) IsomeraseThe question was posed to me during an interview for a job.My doubt is from Water as a Reactant topic in division Water Basics of Biochemistry
Answer» Correct option is (c) Hydrolase For EXPLANATION: Hydrolases, which CATALYZE HYDROLYSIS REACTION involve in food decomposition and in digestion process.

Discussion

19.	Which of the following acids has the lowest pKa value?(a) Acetic acid(b) Sulphuric acid(c) Dil.HCl(d) Oxalic acidThis question was addressed to me in a job interview.Origin of the question is Ionization of Water, Weak acids and Weak Bases topic in section Water Basics of Biochemistry
Answer» RIGHT CHOICE is (b) SULPHURIC ACID To explain: The stronger the acid, the lower its pKa. Sulphuric acid is the strongest acid of all the other acids MENTIONED, so its pKa is the least.

Discussion

20.	ΔG is negative for which of the following processes?(a) Melting of ice and evaporation of water(b) Oxidation of nitrogen(c) Oxidation of gold(d) Burning of chlorineI got this question in a national level competition.The above asked question is from Weak Interactions in Aqueous Systems in section Water Basics of Biochemistry
Answer» The correct option is (a) Melting of ice and evaporation of water The best I can EXPLAIN: The Gibb’s FREE energy change (ΔG) must have a negative value for a process to OCCUR spontaneously. Melting of ice and evaporation of water are the two SPONTANEOUS processes at room temperature.

Discussion

21.	The degree of ionization does not depend on?(a) Temperature(b) Current(c) Nature of solvent(d) ConcentrationI got this question during an online interview.This interesting question is from Ionization of Water, Weak acids and Weak Bases in chapter Water Basics of Biochemistry
Answer» CORRECT answer is (B) Current For explanation I would say: Degree of IONIZATION is INDEPENDENT of current. It depends only on temperature, nature of SOLVENT and concentration.

Discussion

22.	ΔH is positive for which of the following processes?(a) Oxidation of nitrogen(b) Melting of ice and evaporation of water(c) Oxidation of gold(d) Burning of chlorineThis question was posed to me in a job interview.This intriguing question comes from Weak Interactions in Aqueous Systems topic in section Water Basics of Biochemistry
Answer» Correct answer is (B) Melting of ICE and EVAPORATION of water Explanation: ENTHALPY change (ΔH) is positive for endothermic REACTIONS, the reactions which involves absorption of energy. Melting of ice and evaporation of water involves absorption of energy.

Discussion

23.	Calculate the pH of a mixture of 0.10M acetic acid and 0.20M sodium acetate. The pKaof acetic acid is 4.76.(a) 5.1(b) 4.1(c) 6.1(d) 7.1This question was posed to me in my homework.The query is from Buffering against pH changes in Biological Systems topic in section Water Basics of Biochemistry
Answer» Correct CHOICE is (a) 5.1 The explanation: PH = pKa + LOG [acetate]/[acetic ACID] = 4.76 + log (0.2/0.1) = 4.76 + 0.30 = 5.1.

Discussion

24.	Which can act as buffer?(a) NH4 Cl + HCl(b) CH3 COOH + H2 CO3(c) 40ml of 0.1M NaCN + 20ml of 0.1M HCN(d) NaCl + NaOHThe question was asked in an online interview.This intriguing question originated from Buffering against pH changes in Biological Systems in section Water Basics of Biochemistry
Answer» RIGHT answer is (c) 40ML of 0.1M NaCN + 20ml of 0.1M HCN Easy explanation: It is a mixture of WEAK acid and its SALT with STRONG base.

Discussion

25.	K1 and K2 for oxalic acid are 6.5×10^-2and 6.1×10^-5respectively. What will be the [OH^–] in a 0.01M solution of sodium oxalate?(a) 9.6×10^-6(b) 1.4×10^-1(c) 1.2×10^-6(d) 1.3×10^-8I have been asked this question in an interview for internship.My query is from Ionization of Water, Weak acids and Weak Bases in section Water Basics of Biochemistry
Answer» CORRECT OPTION is (C) 1.2×10^-6 To EXPLAIN: The hydrolysis of C2 O4^2- is as follows C2 O4^2-+ H2 O → HC2O^4- + OH^–

Discussion

26.	Which of the following bases has the highest pKa value?(a) NaOH(b) NaNO3(c) KNO3(d) KClThis question was addressed to me in class test.My question is based upon Ionization of Water, Weak acids and Weak Bases in division Water Basics of Biochemistry
Answer» The correct OPTION is (a) NaOH Explanation: The stronger the base, the higher its pKa. NaOH is the STRONGEST base of all the other bases mentioned, so its pKa is the HIGHEST.

Discussion

27.	Identify the triprotic acid from the following.(a) Carbonic acid(b) Bicarbonate(c) Glycine(d) Phosphoric acidI got this question in a national level competition.Question is taken from Ionization of Water, Weak acids and Weak Bases in section Water Basics of Biochemistry
Answer» CORRECT OPTION is (d) PHOSPHORIC ACID The best explanation: Phosphoric acid is triprotic as it can give up THREE protons

Discussion

28.	1M NaCl and 1M HCl are present in an aqueous solution. The solution is ____________(a) Not a buffer solution with pH < 7(b) Not a buffer solution with pH > 7(c) A buffer solution with pH < 7(d) A buffer solution with pH > 7I have been asked this question in a national level competition.This intriguing question comes from Buffering against pH changes in Biological Systems topic in section Water Basics of Biochemistry
Answer» The correct OPTION is (a) Not a buffer solution with PH < 7 Easy explanation: It is a neutral solution and its pH = 7.

Discussion

29.	If pH of solution of NaOH is 12.0 the pH of H2 SO4 solution of same molarity will be?(a) 2.0(b) 12.0(c) 1.7(d) 10.0387The question was asked at a job interview.The origin of the question is Ionization of Water, Weak acids and Weak Bases in division Water Basics of Biochemistry
Answer» RIGHT answer is (C) 1.7 The best I can explain: pH = 12 then pOH = 2 [OH^–] = 10^-2 Molarity of NaOH = 10^-2 For H2 SO4, molarity = 10^-2 [H^+] = 2 × 10^-2 pH = 2 – LOG2 = 1.7.

Discussion

30.	What is the concentration of OH^– in a solution with a H^+ concentration of 1.3×10^-4 M?(a) 7.7×10^-10M(b) 7.7×10^-9M(c) 7.7×10^-11M(d) 7.7×10^-12MThis question was posed to me in an interview.Question is taken from Ionization of Water, Weak acids and Weak Bases topic in portion Water Basics of Biochemistry
Answer» The CORRECT ANSWER is (c) 7.7×10^-11M To explain I would say: Kw = [H^+][OH^–] SOLVING for [OH^–]gives [OH^–]=(Kw)/([H^+]) = (1.0 X 10^-14)/(1.3 X 10^-4) M = 7.7 × 10^-11M.

Discussion

31.	Which of the following is not a condensation reaction?(a) ADP + inorganic phosphateATP + H2O(b) R-OH + inorganic phosphatephosphate ester + H2O(c) R-COOH + inorganic phosphateAcyl phosphate + H2O(d) 6CO2 + 6 H2OC6H12O6 + 6CO2The question was posed to me in an online interview.This key question is from Water as a Reactant in chapter Water Basics of Biochemistry
Answer» CORRECT answer is (d) 6CO2 + 6 H2OC6H12O6 + 6CO2 Easiest EXPLANATION: CONDENSATION reaction involves ELIMINATION of water MOLECULES.

Discussion

32.	Calculate the pKaof lactic acid, given that when the concentration of lactic acid is 0.010M and the concentration of lactate is 0.087M, the pH is 4.80.(a) 4.0(b) 3.9(c) 3.3(d) 4.1I had been asked this question in an online quiz.Asked question is from Buffering against pH changes in Biological Systems topic in section Water Basics of Biochemistry
Answer» Right OPTION is (b) 3.9 To explain I would SAY: PH = pKa + log [lactate]/[LACTIC ACID] pKa = pH – log [lactate]/[lactic acid] = 4.80 – log (0.087/0.010) = 4.80 – log 8.7 = 3.9.

Discussion

Explore topic-wise InterviewSolutions in .

Which of the following is an isotonic solution?(a) 0.9% sodium chloride(b) 0.45% sodium chloride(c) Oceans(d) 10% dextrose in waterI had been asked this question during an interview.The question is from Weak Interactions in Aqueous Systems topic in portion Water Basics of Biochemistry

The buffer capacity is equal to __________(a) Δn / ΔpH(b) pH / Δn(c) ± 1pKa(d) ± 2pKaThe question was posed to me during an online exam.My doubt stems from Buffering against pH changes in Biological Systems topic in portion Water Basics of Biochemistry

The bond dissociation energy of hydrogen bonds in a water molecule is ______________(a) 470 kJ/mole(b) 470 J/mole(c) 23 kJ/mole(d) 23 J/moleI got this question in class test.This is a very interesting question from Weak Interactions in Aqueous Systems in portion Water Basics of Biochemistry

Which of the following does not react with water?(a) Barium(b) Calcium(c) Beryllium(d) StrontiumI have been asked this question by my school principal while I was bunking the class.Asked question is from Water as a Reactant topic in division Water Basics of Biochemistry

The hydrolysis constant of CH3COONa is given by ____________(a) Kh = Kw/Ka(b) Kh = Kw/Kb(c) Kh = Kw/Ka×Kb(d) Kh =Ka +KbI got this question during an interview.This intriguing question comes from Ionization of Water, Weak acids and Weak Bases in chapter Water Basics of Biochemistry

Aqueous solution of the detergents are _________(a) Neutral(b) Acidic(c) Basic(d) AmphotericI had been asked this question during an interview.I need to ask this question from Ionization of Water, Weak acids and Weak Bases topic in division Water Basics of Biochemistry

Which of the following is the correct equation?(a) CO2 + H2O H2CO3(b) CO2 + H2O HCO3(c) CO2 + H2O H3CO3(d) CO2 + H2O H2CO2This question was posed to me in unit test.This intriguing question originated from Water as a Reactant in division Water Basics of Biochemistry

What is the heat of vaporization of water?(a) 2260 J/g(b) 2260 kJ/g(c) 1260 J/g(d) 1260 kJ/gI got this question by my school teacher while I was bunking the class.Query is from Weak Interactions in Aqueous Systems in section Water Basics of Biochemistry

Hydrolysis reactions are catalyzed by enzymes called ___________(a) Oxidoreductase(b) Ligase(c) Hydrolase(d) IsomeraseThe question was posed to me during an interview for a job.My doubt is from Water as a Reactant topic in division Water Basics of Biochemistry

Which of the following acids has the lowest pKa value?(a) Acetic acid(b) Sulphuric acid(c) Dil.HCl(d) Oxalic acidThis question was addressed to me in a job interview.Origin of the question is Ionization of Water, Weak acids and Weak Bases topic in section Water Basics of Biochemistry

The degree of ionization does not depend on?(a) Temperature(b) Current(c) Nature of solvent(d) ConcentrationI got this question during an online interview.This interesting question is from Ionization of Water, Weak acids and Weak Bases in chapter Water Basics of Biochemistry

Calculate the pH of a mixture of 0.10M acetic acid and 0.20M sodium acetate. The pKaof acetic acid is 4.76.(a) 5.1(b) 4.1(c) 6.1(d) 7.1This question was posed to me in my homework.The query is from Buffering against pH changes in Biological Systems topic in section Water Basics of Biochemistry

Which can act as buffer?(a) NH4 Cl + HCl(b) CH3 COOH + H2 CO3(c) 40ml of 0.1M NaCN + 20ml of 0.1M HCN(d) NaCl + NaOHThe question was asked in an online interview.This intriguing question originated from Buffering against pH changes in Biological Systems in section Water Basics of Biochemistry

Which of the following bases has the highest pKa value?(a) NaOH(b) NaNO3(c) KNO3(d) KClThis question was addressed to me in class test.My question is based upon Ionization of Water, Weak acids and Weak Bases in division Water Basics of Biochemistry

Identify the triprotic acid from the following.(a) Carbonic acid(b) Bicarbonate(c) Glycine(d) Phosphoric acidI got this question in a national level competition.Question is taken from Ionization of Water, Weak acids and Weak Bases in section Water Basics of Biochemistry

If pH of solution of NaOH is 12.0 the pH of H2 SO4 solution of same molarity will be?(a) 2.0(b) 12.0(c) 1.7(d) 10.0387The question was asked at a job interview.The origin of the question is Ionization of Water, Weak acids and Weak Bases in division Water Basics of Biochemistry