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Equilibrium Class 11 MCQs Questions with Answers
Multiple Choice Type Questions
Question 1.
Consider the following equilibrium in a closed container N2O4 (g) ⇌ 2NO2 (g).
At a fixed temperature, the volume of the reaction container is halved. For this change, which of the following statements hold true regarding the equilibrium constant (Kp) and degree of dissociation (α)?
(a) Neither Kp nor α changes
(b) Both Kp and α change
(c) Kp changes but α does not change
(d) Kp does not change but α changes.
Answer
Answer: (b) Both Kp and α change
Question 2.
For the reversible reaction
N2(g) + 3H2(g) ⇌ 2NH2(g)
at 500°C, the value of Kp is 1.44 × 10-5. when the partial pressure is measured in atmosphere, the corresponding value of Kc. with concentration in mol L-1 is
(a) 1.44 × 10-5/(0.082 × 500)-2
(b) 1.44 × 10-5/(8.314 × 773)-1
(c) 1.44 × 10-5/(0.082 × 773)-1
(d) 1.44 × 10-5/(0.082 × 772)-2
Answer
Answer: (d) 1.44 × 10-5/(0.082 × 772)-2
Question 3.
When two reactants A and B are mixed to give products C and D, the concentration quotient (Q) at initial stage of the reaction
(a) Is zero
(b) Decreases with time
(c) Is independent of time
(d) Increases with time.
Answer
Answer: (d) Increases with time.
Question 4.
At constant temperature, the equilibrium constant (Kp) for the decomposition reaction
N2O4 ⇌ 2NO2 is expressed by
Kp = \(\frac {4x^2P}{(1-x^2)}\) P
where P = pressure, x = extent of decomposition.
Which one of the following statements is true?
(a) Kp increases with increase of P
(b) Kp increases with increase of x
(c) Kp decreases with decrease of x
(d) Kp remains constant with change in P and x.
Answer
Answer: (b) Kp increases with increase of x
Question 5.
For the chemical reaction
3X (g) + Y (g) ⇌ X3Y (g)
the amount of X3Y at equilibrium is affected by
(a) Temperature and pressure
(b) Pressure only
(c) Temperature only
(d) Temperature, pressure and catalyst.
Answer
Answer: (a) Temperature and pressure
Question 6.
ZnCO3 (s) ⇌ ZnO (s) + CO2 (g) Expression of the partial pressure of the above reaction is
2A + B s, C, the units of Kp is
(a) Kp = \(\frac {[ZnO][CO_2]}{[ZnCO_3]}\)
(b) Kp = \(\frac {[ZnO]p[CO_2]}{p[ZnCO_3]}\)
(c) Kp = p\(_{(ZnO)p(CO_2)}^{2}\)
(d) Kp = pCO2
Answer
Answer: (d) Kp = pCO2
Question 7.
For the chemical reaction:
2A + B ⇌ C, the units of Kp is
(a) atm-2
(b) atm-3
(c) atm-1
(d) Dimensionless
Answer
Answer: (a) atm-2
Question 8.
In which manner, the increase of the pressure will affect the following equilibrium?
C(s) + H2O (g) ⇌ CO (g) + H2 (g)
(a) Shifts in the forward direction
(b) Shifts in the reverse direction
(c) Increase the yield of hydrogen
(d) No effect.
Answer
Answer: (b) Shifts in the reverse direction
Question 9.
One mole of N2O4 (g) at 300 K is kept in a closed container under one atmosphere. It is heated to 600 K when 20% by mass of N2O4 (g) decomposes to NO2 (g). The resultant pressure is
(a) 1.2 atm
(b) 2.4 atm
(c) 2.0 atm
(d) 1.0 atm.
Answer
Answer: (b) 2.4 atm
Question 10.
The following equilibria are given
N2 + 3H2 ⇌ 2NH3 K1
N2 + O2 ⇌ 2NO K2
H2 + 1/2O2 ⇌ H2O K3
The equilibrium constant for the reaction
2NH3 + \(\frac {5}{2}\)O2 ⇌ 2NO + 3H2O
in terms of K1, K2, K3, is
(a) K1 K2 K3
(b) K1 K2/K3
(c) K1 K\(_{3}^{2}\)/K2
(d) K2K\(_{3}^{2}\)/K1
Answer
Answer: (d) K2K\(_{3}^{2}\)/K1
Question 11.
Kp/Kc for the reaction CO (g) + \(\frac {1}{2}\) O2 (g) ⇌ CO2 (g) is
(a) 1
(b) RT
(c) l/\(\sqrt {RT}\)
(d) (RT)1/2
Answer
Answer: (c) l/\(\sqrt {RT}\)
Question 12.
In the reaction PCl5 (g) ⇌ PCl3 (g) + Cl2 (g) the equilibrium concentrations of PCl5 and PCl3 are 0.4 and 0.2 mole/litre respectively. If the value of Kc. is 0.5, what is the concentration of Cl2 in moles/ litre?
(a) 2.0
(b) 1.5
(c) 1.0
(d) 0.5
Answer
Answer: (c) 1.0
Question 13.
The reaction quotient (Q) for the reaction
N2 (g) + 3H2 (g) ⇌ 2NH3 (g) is given by
Q = [NH3]²/[N2][H2]³
The reaction will proceed from right to left if
(a) Q = Kc.
(b) Q < Kc
(c) Q > Kc.
(d) Q = 0
Answer
Answer: (c) Q > Kc.
Question 14.
In which of the following equilibrium, change in the volume of the system does not alter the number of moles?
(a) N2 (g) + O2 (g) ⇌ 2NO (g)
(b) PCl5 (g) ⇌ PCl3 (g) + Cl2 (g)
(c) N2(g) + 3H2 ⇌ 2NH3 (g)
(d) SO2Cl2 (g) ⇌ SO2 (g) + Cl2 (g)
Answer
Answer: (a) N2 (g) + O2 (g) ⇌ 2NO (g)
Question 15.
1 mole of N2 and 2 moles of H2 are allowed to react in a 1 dm³ vessel. At equilibrium 0.8 mole of NH3 is formed. The concentration of H2 in the vessel is
(a) 0.6 mole
(b) 0.8 mole
(c) 0.2 mole
(d) 0.4 mole.
Answer
Answer: (b) 0.8 mole
Question 16.
The rate of forward reaction is two times that of the reverse reaction at a given temperature and identical concentration, k(equilibrium) is
(a) 0.5
(b) 1.5
(c) 2.5
(d) 2.0
Answer
Answer: (d) 2.0
Question 17.
For a reversible reaction, if the concentrations of the reactants are doubled, the equilibrium constant will be
(a) halved
(b) doubled
(c) the same
(d) one fourth
Answer
Answer: (c) the same
Question 18.
If N2 (g) + 3H2 (g) ⇌ 2NH3 (g); K, then
2N2 (g) + 6H2 (g) ⇌ 4NH3; K-1
(a) K²
(b) √K
(c) 1/√K
(d) 1/K²
Answer
Answer: (a) K²
Question 19.
In the case of a gaseous homogeneous reaction, the active mass of the reactant is obtained by the expression
(a) PV/RT
(b) P/RT
(c) RT/P
(d) \(\frac {n}{V}\) RT
Answer
Answer: (b) P/RT
Question 20.
For the reaction N2 + 3H2 ⇌ 2NH3 + heat
(a) Kp = K.(RT)2-
(b) Kp = Kc
(c) Kp = KcRT
(d) Kp = Kc (RT)-1
Answer
Answer: (a) Kp = K.(RT)2-
Question 21.
What happens to the yield of this reaction when temperature is increased?
N2 + O2 ⇌ 2NO; 43 k cal
(a) increases
(b) decreases
(c) remains same
(d) none of these
Answer
Answer: (a) increases
Question 22.
The pH of 10-8 M HCl is
(a) 8
(b) 7
(c) between 7 and 8
(d) between 6 and 7
Answer
Answer: (d) between 6 and 7
Question 23.
The Ksp for HgS, Ag2S and PbS are 10-3, 10-45 and 10-50 respectively. The solubilities are in the order
(a) HgS > Ag2S > PbS
(b) HgS < PbS < Ag2S
(c) PbS > Ag2S > HgS
(d) Ag2S > HgS > PbS
Answer
Answer: (d) Ag2S > HgS > PbS
Question 24.
The solubility of M2S is 3.5 × 10-6. The solubility product of the salt is
(a) 1.7 × 10-6
(b) 3.4 × 10-16
(c) 1.7 × 10-16
(d) 6.8 × 10-12
Answer
Answer: (c) 1.7 × 10-16
Question 25.
Aluminium chloride is
(a) Bronsted Lowry acid
(b) Arrhenius acid
(c) Lewis acid
(d) Lewis base
Answer
Answer: (c) Lewis acid
Question 26.
A buffer solution with pH more than 9 can be prepared by mixing
(a) CH3COONa and CH3COOH
(b) NaCl and NaOH
(c) NH4Cl and NaOH
(d) KH2PO4 and K2HPO4
Answer
Answer: (a) CH3COONa and CH3COOH
Question 27.
A base according to Bronsted concept is a substance which can
(a) lose a pair of electrons
(b) donate protons
(c) gain a pair of electrons
(d) accept protons.
Answer
Answer: (d) accept protons.
Question 28.
For a sparingly soluble salt ApBq the relationship between its solubility product (Ls) and its solubility (s) is
(a) Ls = sp+q ppqq
(b) Ls = sp+q Pqqp
(c) Ls = spqPpqq
(d) Ls = spq (pq)q+p
Answer
Answer: (a) Ls = sp+q ppqq
Question 29.
Which is not Lewis acid?
(a) BF3
(b) AgCl
(c) BeCl2
(d) MgCl2
Answer
Answer: (d) MgCl2
Question 30.
To Ag2CrO4 solution over its own precipitate, CrO\(_{4}^{2-}\) ions are added. This results in
(a) increase in Ag+ concentration
(b) decrease in Ag+ concentration
(c) increase in solubility product
(d) decrease in solubility product
Answer
Answer: (b) decrease in Ag+ concentration
Question 31.
When sodium carbonate solution is titrated against HCl
solution, the indicator used is
(a) Phenolphthalein
(b) Methyl orange
(c) Methyl red
(d) Starch.
Answer
Answer: (b) Methyl orange
Question 32.
In the reaction
NH3 + H2O ⇌ NH\(_{2}^{-}\) + H3O+
The conjugate base of NH3 is
(a) H3O–
(b) NH\(_{2}^{-}\)
(c) H2O
(d) None of these
Answer
Answer: (b) NH\(_{2}^{-}\)
Question 33.
The pH of a solution of hydrochloric acid is 4. The molarity of the solution is
(a) 4.0
(b) 0.4
(c) 0.0001
(d) 0.04
Answer
Answer: (c) 0.0001
Question 34.
In the reaction
I2 + I– → I\(_{3}^{-}\)
the Lewis base is
(a) I2
(b) I–
(c) I\(_{3}^{-}\)
(d) None of these
Answer
Answer: (b) I–
Question 35.
The pH of a 0.005 M aqueous solution of sulphuric acid is
(a) 0.005
(b) 2
(c) 1
(d) 0.01
Answer
Answer: (b) 2
Question 36.
CO2 is
(a) Lewis acid
(b) Lewis base
(d) Bronsted acid
(d) Bronsted base.
Answer
Answer: (a) Lewis acid
Question 37.
Which of the following is a Lewis base?
(a) AlCl3
(b) Ag+
(c) Al(OH)3
(d) NH3
Answer
Answer: (d) NH3
Question 38.
Solubility of Pbl2 is 0.0013 M. Then solubility product of Pbl2 is
(a) 2.2 × 10-9
(b) 8.8 × 10-9
(c) 6.8 × 10-6
(d) 8.8 × 10-6
Answer
Answer: (b) 8.8 × 10-9
Question 39.
The solubility product of Agl as 25°C is 1.0 × 10-16 mol² L-2. The solubility of Agl in 10-14 N solution of KI at 25°C is approx, (in mol L-1)
(a) 1.0 × 10-6
(b) 1.0 × 10-12
(c) 1.0 × 10-10
(d) 1.0 × 10-8
Answer
Answer: (b) 1.0 × 10-12
Question 40.
In the hydrolysis of a salt of weak acid and weak base the hydrolysis constant Kb is equal to
(a) Kw/Kb
(b) Kb/Kw
(c) Kw/Kab
(d) KaKb
Answer
Answer: (c) Kw/Kab
Question 41.
Water is a
(a) Protophobic solvent
(b) Protophilic solvent
(c) Amphiprotic solvent
(d) Aprotic solvent
Answer
Answer: (c) Amphiprotic solvent
Question 42.
Among the following, the weakest -base is
(a) H
(b) CH\(_{3}^{-}\)
(c) CH3O–
(d) Cl–
Answer
Answer: (d) Cl–
Question 43.
Which of the following is the buffer solution of strong acidic nature?
(a) HCOOH + HCOO–
(b) CH4COOH + CH3COO–
(c) H3C3O4 + C2O\(_{4}^{2-}\)
(d) H3BO3 + BO\(_{3}^{3}\)
Answer
Answer: (a) HCOOH + HCOO–
Question 44.
Which of the following has highest pH?
(a) CH3COOK
(b) Na2CO3
(c) NH4Cl
(d) NaNO3
Answer
Answer: (b) Na2CO3
Question 45.
The pH range of methyl red indicator is
(a) 4.2 of 6.3
(b) 8.3 and 10
(c) 8.0 to 9.6
(d) 6.8 to 8.4
Answer
Answer: (a) 4.2 of 6.3
Question 46.
How do you differentiate between Fe3+ and Cr3+ ion in group III?
(a) By taking excess of NH4OH
(b) By increasing NH\(_{4}^{+}\) concentration
(c) By decreasing OH ions concentration
(d) both (b) and (c).
Answer
Answer: (d) both (b) and (c).
Question 47.
Solubility of an MX2 type electrolyte is 0.5 × 10-4 mol L-1, then Ksp of the electrolyte is
(a) 5 × 10-12
(b) 25 × 10-10
(c) 1 × 10-13
(d) 5 × 10-13
Answer
Answer: (d) 5 × 10-13
Question 48.
In which of the following acid-base titration pH is greater than 8 at the equivalent point.
(a) Acetic acid Vs ammonia
(b) Acetic acid Vs sodium hydroxide
(c) Hydrochloric acid Vs sodium hydroxide.
Answer
Answer: (b) Acetic acid Vs sodium hydroxide
Question 49.
When rain is accompanied by a thunderstorm, the collected rain water will have pH value
(a) slightly higher than that when the thunderstorm is not there.
(b) uninfluenced by the thunderstorm
(c) which depends upon the amount of dust in air
(d) slightly lower than that of rain water without thunderstorm.
Answer
Answer: (d) slightly lower than that of rain water without thunderstorm.
Question 50.
The pH of 0.1 M aqueous solution of a weak acid (HA) is 3. What is its degree of dissociation?
(a) 1%
(b) 10%
(c) 50%
(d) 25%
Answer
Answer: (a) 1%
Question 51.
A solution which is 10-3 M each in Mn2+, Fe2+, Zn2+ and Hg2+ is treated with 10-16 M sulphide ion. If Ksp of MnS, FeS, ZnS and HgS are 10-15, 10-23, 10-20 and 10-54 respectively, which one will precipitate first.
(a) FeS
(b) MgS
(c) HgS
(d) ZnS
Answer
Answer: (c) HgS
Fill in the blanks
Question 1.
If the equilibrium constant for the reaction N2 + 3H2 ⇌ 2NH3 is K, then eqbm. constant for the reaction \(\frac {1}{2}\) N2 + \(\frac {3}{2}\) H2 ⇌ NH3 is K’ = ………………
Answer
Answer: √K
Question 2.
Kp and Kc are related to each other by Kc = ………………..
Answer
Answer: Kp(RT)∆n
Question 3.
If the value of eqbm. constant for the reaction CH3COOH + C2H5OH ⇌ CH3COOC2H5 + H2O is 4, then eqbm. constant for the reverse reaction will be …………………
Answer
Answer: \(\frac {1}{4}\)
Question 4.
PH, pOH and pkw are related to each other by the relationship ……………….
Answer
Answer: pH + pOH = pka
Question 5.
Kp for the reaction CaCO3 (s) ⇌ CaO (s) + CO2 (g) is = ………………….
Answer
Answer: PCO2
Question 6.
If Q < K, Q will tend to ……………….. As a result the reaction will proceed in the ……………… direction.
Answer
Answer: increase, forward
Question 7.
Exothermic reactions are favoured by ………………… temperature whereas endothermic reactions are favoured by ………………. temperature.
Answer
Answer: low, high
Question 8.
A reaction which proceeds with a decrease in volume, is favoured by …………………. pressure.
Answer
Answer: high
Question 9.
The fraction of the total salt hydrolysed is called the ………………..
Answer
Answer: degree of hydrolysis
Question 10.
h- the degree of hydrolysis, Kh – the hydrolysis constant and the concentration of the aqueous solution of a salt (C) are related to each other by the expression ………………
Answer
Answer: h = \(\sqrt {K_h/c}\)
Write True / False
Question 1.
pH of a soap solution is less than 7.
Answer
Answer: False
Question 2.
pH of lemon juice is greater than 7.
Answer
Answer: False
Question 3.
pH of a solution of sodium nitrate in water is equal to 7.
Answer
Answer: True
Question 4.
H+ ions concentration of water 298 K is 1.0 × 10-7 mole L-1
Answer
Answer: True
Question 5.
An exothermic reaction is favoured with decrease in temperature.
Answer
Answer: True
Question 6.
pH + pOH = 14.
Answer
Answer: True
Question 7.
Addition of a catalyst increases the formation of NH3 in the reaction N2 + 3H2 ⇌ 2NH3.
Answer
Answer: False
Question 8.
For the reaction H2 (g) + I2 (g) ⇌ 2HI (g),
Kp = K
Answer
Answer: True
Question 9.
The equilibrium constant of a reaction is 2 × 10-3 at 25°C and 2 × 10-2 at 50°C. This reaction is exothermic.
Answer
Answer: False
Question 10.
A low pressure in the reaction PCl5 (g) ⇌ PCl3 (g) + Cl2 (g) will increase the degree of dissociation of PCl5 (g).
Answer
Answer: True
Question 11.
Increase or decrease of pressure has no effect on the reaction
N2 (g) + O2 (g) ⇌ 2NO (g).
Answer
Answer: True
Match the Following
| Column I |
Column II |
| 1. N2 + 3H2 ⇌ 2NH3 + 92.5 kj |
(i) Kc = Kp |
| 2. N2 + O2 ⇌ 2NO; Kc = 4.8 × 10-31 at 298 K |
(ii) Low temperature favours the formation of products. |
| 3. 2NO2 (g) ⇌ N2O2 (g) ∆H = -57.2 kj mol-1 |
(iii) More of the reactants are present at equilibrium. |
| 4. H2 (g) + I2 (g) ⇌ 2HI(g) |
(iv) Colour changes from reddish brown to colourless. |
Answer
Answer:
| Column I |
Column II |
| 1. N2 + 3H2 ⇌ 2NH3 + 92.5 kj |
(ii) Low temperature favours the formation of products. |
| 2. N2 + O2 ⇌ 2NO; Kc = 4.8 × 10-31 at 298 K |
(iii) More of the reactants are present at equilibrium. |
| 3. 2NO2 (g) ⇌ N2O2 (g) ∆H = -57.2 kj mol-1 |
(iv) Colour changes from reddish brown to colourless. |
| 4. H2 (g) + I2 (g) ⇌ 2HI(g) |
(i) Kc = Kp |
| Column I |
Column II |
| 1. N2 + 3H2 ⇌ 2NH3; ∆H = -92.5 KJ |
(i) Increase of temperature will shift the equilibrium forward. |
| 2. H2 (g) + CO (g) + H2O (g) ⇌ 2H2 (g) + CO2 (g) ∆H = +42.0 KJ |
(ii) Increase of pressure will shift the equilibrium forward |
| 3. N2O4 + 58.6 KJ ⇌ 2NO2 |
(iii) Pressure has no effect. |
| 4. CH3COOH + C2H5OH ⇌ CH3COOC2H5 + H2O |
(iv) Decrease of pressure will shift the eqbm. forward. |
Answer
Answer:
| Column I |
Column II |
| 1. N2 + 3H2 ⇌ 2NH3; ∆H = -92.5 KJ |
(ii) Increase of pressure will shift the equilibrium forward |
| 2. H2 (g) + CO (g) + H2O (g) ⇌ 2H2 (g) + CO2 (g) ∆H = +42.0 KJ |
(i) Increase of temperature will shift the equilibrium forward. |
| 3. N2O4 + 58.6 KJ ⇌ 2NO2 |
(iv) Decrease of pressure will shift the eqbm. forward. |
| 4. CH3COOH + C2H5OH ⇌ CH3COOC2H5 + H2O |
(iii) Pressure has no effect. |
| Column I |
Column II |
| 1. Milk |
(i) 2.2 |
| 2. Human saliva |
(ii) 6.4 |
| 3. Human blood |
(iii) 6.8 |
| 4. Lemon juice |
(iv) 7.4 |
Answer
Answer:
| Column I |
Column II |
| 1. Milk |
(iii) 6.8 |
| 2. Human saliva |
(ii) 6.4 |
| 3. Human blood |
(iv) 7.4 |
| 4. Lemon juice |
(i) 2.2 |
| Column I |
Column II |
| 1. Methyl alcohol(CH3OH) |
(i) Protophilic |
| 2. Benzene (C6H6) |
(ii) Protogenic |
| 3. Ammonia (NH3) |
(iii) Amphiprotic |
| 4. Acetic acid (CH3COOH) |
(iv) Aprotic |
Answer
Answer:
| Column I |
Column II |
| 1. Methyl alcohol(CH3OH) |
(i) Protophilic |
| 2. Benzene (C6H6) |
(iv) Aprotic |
| 3. Ammonia (NH3) |
(iii) Amphiprotic |
| 4. Acetic acid (CH3COOH) |
(ii) Protogenic |
| Column I |
Column II |
| 1. Lunar caustic |
(i) 7 |
| 2. Washing soda solution |
(ii) <7 |
| 3. Table salt solution |
(iii) >7 |
| 4. Thomas slag solution |
(iv) Nearly 7 |
Answer
Answer:
| Column I |
Column II |
| 1. Lunar caustic |
(ii) <7 |
| 2. Washing soda solution |
(iii) >7 |
| 3. Table salt solution |
(i) 7 |
| 4. Thomas slag solution |
(iv) Nearly 7 |
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