CBSE Class 11 Chemistry Equilibrium Worksheet

Equilibrium MCQ Questions with Answers Class 11 Chemistry 

Question- Suitable conditions for melting of ice :

(a) high temperature and high pressure

(b) high temperature and low pressure

(c) low temperature and low pressure

(d) low temperature and high pressure

Answer-(a)

Question-In a reversible chemical reaction having two reactants in equilibrium, if the concentration of the reactants are doubled then the equilibrium constant will

(a) Also be doubled

(b) Be halved

(c) Become one-fourth

(d) Remain the same

Answer-(d)

Question- Boiling point of the liquid depends on the atmospheric pressure. It depends on the altitude of the place; at high altitude the boiling point…………..

(a) increases

(b) decreases

(c) either decreases or increases

(d) remains same

Answer-(b)

Question-In an experiment three watch glasses containing separately 1mL each of acetone, ethyl alcohol, and water are exposed to atmosphere and the experiment with different volumes of the liquids in a warmer room is repeated, it is observed that in all such cases the liquid eventually disappears and the time taken for complete evaporation in each case was different. The possible reason is/are

(a) the nature of the liquids is different

(b) the amount of the liquids is different

(c) the temperature is different

(d) All of the above

Answer-(d)

Question-On doubling P and V with constant temperature the equilibrium constant will

(a) remain constant

(b) become double

(c) become one-fourth

(d) None of these

Answer-(a)

Question-When pressure is applied to the equilibrium system Ice ↔ Water Which of the following phenomenon will happen?

(a) More ice will be formed

(b) Water will evaporate

(c) More water will be formed

(d) Equilibrium will not be formed

Answer-(c)

Question-Which of the following is not true about a reversible reaction?

(a) The reaction does not proceed to completion

(b) It cannot be influenced by a catalyst

(c) Number of moles of reactants and products is always equal

(d) It can be attained only in a closed container

Answer-(c)

Question-If the synthesis of ammonia from Haber's process is carried out with exactly the same starting conditions (of partial pressure and temperature) but using D₂ (deuterium) in place of H₂. Then

(a) the equilibrium will be disturbed

(b) the composition of reaction mixture will remain same at equilibrium.

(c) Use of isotope in reaction will not produce ammonia.

(d) At equilibrium rate of forward reaction will be greater than the rate of reverse reaction

Answer-(b)

Question-The reaction quotient Q is used to

(a) predict the extent of a reaction on the basis of its magnitude

(b) predict the direction of the reaction

(c) calculate equilibrium concentrations

(d) calculate equilibrium constant

Answer-(b)

Question- A small amount of acetone is taken in a watch glass and it is kept open in atmosphere. Which statement is correct for the given experiment?

(a) The rate of condensation from vapour to liquid state is higher than the rate of evaporation

(b) The rate of condensation from vapour to liquid state is equal to the rate of evaporation.

(c) The rate of condensation from vapour to liquid state is much less than the rate of evaporation.

(d) The rate of condensation from vapour to liquid state is equal or less than the rate of evaporation.

Answer-(c)

Question-In an equilibrium reaction if temperature increases

(a) equilibrium constant increases

(b) equilibrium constant decreases

(c) any of the above

(d) no effect 

Answer-(c)

Question- Which of the following is not a general characteristic of equilibria involving physical processes ?

(a) Equilibrium is possible only in a closed system at a given temperature.

(b) All measurable properties of the system remain constant.

(c) All the physical processes stop at equilibrium.

(d) The opposing processes occur at the same rate and there is dynamic but stable condition.

Answer-(c)

Question-What happens when an inert gas is added to an equilibrium keeping volume unchanged?

(a) More product will form

(b) Less product will form

(c) More reactant will form

(d) Equilibrium will remain unchanged

Answer-(a)

Question- A reaction is said to be in equilibrium when

(a) the rate of transformation of reactant to products is equal to the rate of transformation of products to the reactants.

(b) 50% of the reactants are converted to products.

(c) the reaction is near completion and all the reactants are converted to products.

(d) the volume of reactants is just equal to the volume of the products.

Answer-(a)

Question-The liquid which has a ………..vapour pressure is more volatile and has a ………….boiling point.

(a) Higher , higher

(b) Lower, lower

(c) Higher, lower

(d) Lower, higher

Answer-(c)

Equilibrium MCQ Questions with Answers Class 11 Chemistry

Question- In a vessel N₂, H₂ and NH₃ are at equilibrium. Some helium gas is introduced into the vessel so that total pressure increases while temperature and volume remain constant. According to Le Chatelier’s principle, the dissociation of NH3

(a) increases

(b) decreases

(c) remains unchanged

(d) equilibrium is disturbed

Answer-(c)

Question-Which of the following molecules acts as a Lewis acid ?

(a) (CH₃)₂ O

(b) (CH₃)₃ P

(c) (CH₃)₃ N

(d) (CH₃)₃ B

Answer-(d)

Question- Which of the following statements are correct regarding Arrhenius theory of acid and base?

(a) This theory was applicable to only aqueous solutions

(b) This theory was applicable to all solutions

(c) This theory could not explain the basicity of substances like ammonia which do not possess a hydroxyl group

(d) Both (a) and (c)

Answer-(d)

Question-An acid/ base dissociation equilibrium is dynamic involving a transfer of proton in forward and reverse directions. Now, with passage of time in which direction equilibrium is favoured ?

(a) in the direction of stronger base and stronger acid

(b) in the direction of formation of stronger base and weaker acid

(c) in the direction of formation of weaker base and weaker acid

(d) in the direction of formation of weaker base and stronger acid

Answer-(c)

Question-Would gaseous HCl be considered as an Arrhenius acid ?

(a) Yes

(b) No

(c) Not known

(d) Gaseous HCl does not exist

Answer-(b)

Question-BF₃ is an acid according to

(a) Arrhenius concept

(b) Bronsted-Lowry concept

(c) Lewis Concept

(d) Both (b) and (c)

Answer-(c)

Question- Which of the following is/are electrolytes?
(i) Sugar solution (ii) Sodium chloride
(iii) Acetic acid (iv) Starch solution

(a) (i) and (iv)

(b) (ii) and (iv)

(c) (ii) and (iii)

(d) (i) and (iii)

Answer-(c)

Question-Effect of a catalyst on a equilibrium reaction.

(i) A catalyst increases the rate of the chemical reaction by making available a new low energy pathway for the conversion of reactants to products.
(ii) It increases the rate of forward and reverse reactions that pass through the same transition state and does not affect equilibrium.
(iii) It lowers the activation energy for the forward and reverse reactions by exactly the same amount.

Which of the above statement(s) is/are correct ?

(a) Only (i)

(b) (i) and (ii)

(c) (i), (ii) and (iii)

(d) (ii) and (iii)

Answer-(c)

Question-Conjugate acid of NH₂^- NH is :

(a) NH₄⁺

(b) NH₃

(c) NH₂

(d) NH

Answer-(b)

Question-Among boron trifluoride, stannic chloride and stannous chloride, Lewis acid is represented by

(a) only stannic chloride

(b) boron trifluoride and stannic chloride

(c) boron trifluoride and stannous chloride

(d) only boron trifluoride

Answer-(c)

Question-Which one of the following molecular hydrides acts as a Lewis acid?

(a) NH₃

(b) H₂O

(c) B₂H₆

(d) CH₄

Answer-(c)

Question-A base, as defined by Bronsted theory, is a substance which can

(a) lose a pair of electrons

(b) donate protons

(c) gain a pair of electrons

(d) accept protons

Answer-(d)

Question- Which of the following can act as both Bronsted acid and Bronsted base?

(a) Na₂CO₃

(b) OH^–

(c) HCO₃^–

(d) NH₃

Answer-(c)

Question-Which one of the following is the correct statement ?

(a) HCO₃^– is the conjugate base of CO₃^2–.

(b) NH₂^– is the conjugate acid of NH₃.

(c) H₂SO₄ is the conjugate acid of HSO₄^–.

(d) NH₃ is the conjugate base of NH₂^–

Answer-(c)

Question-The value of the ionic product of water

(a) depends on volume of water

(b) depends on temperature

(c) changes by adding acid or alkali

(d) always remains constant

Answer-(b)

Question-A base when dissolved in water yields a solution with a hydroxyl ion concentration of 0.05 mol litre^–1. The solution is

(a) basic

(b) acidic

(c) neutral

(d) either (b) or (c)

Answer-(a)

Question-The geometry of hydronium ion is

(a) tetrahedral

(b) linear

(c) trigonal pyramidal

(d) trigonal planer

Answer-(c)

Question-pH scale was introduced by :

(a) Arrhenius

(b) Sorensen

(c) Lewis

(d) Lowry

Answer-(b)

Question-Which of these is least likely to act as Lewis base?

(a) F^–

(b) BF₃

(c) PF₃

(d) CO

Answer-(b)

Equilibrium MCQ Questions with Answers Class 11 Chemistry

Question- A weak acid, HA, has a Ka of 1.00 × 10^–5. If 0.100 mole of this acid dissolved in one litre of water, the percentage of acid dissociated at equilbrium is closest to

(a) 1.00%

(b) 99.9%

(c) 0.100%

(d) 99.0%

Answer-(a)

Question-The pH of a 10^–3 M HCl solution at 25°C if it is diluted 1000 times, will be –

(a) 3

(b) zero

(c) 5.98

(d) 6.02

Answer-(c)

Question-Cationic hydrolysis gives the following solution:

(a) acidic

(b) basic

(c) neutral

(d) amphoteric

Answer-(a)

Question-The pH of 0.005 molar solution of H₂SO₄ is approximately:

(a) 0.010

(b) 1

(c) 2

(d) 0.005

Answer-(c)

Question-What is the approximate pH of a 1 × 10^–3 M NaOH solution?

(a) 3

(b) 11

(c) 7

(d) 1 × 10^–11

Answer-(b)

Question-A monobasic weak acid solution has a molarity of 0.005 and pH of 5. What is the percentage ionization in this solution?

(a) 2.0

(b) 0.2

(c) 0.5

(d) 0.25

Answer-(b)

Question-In qualitative analysis, in III group NH₄Cl is added before NH4OH because

(a) to increase the concentration of NH4+ions

(b) to increase concentration of Cl^– ions

(c) to reduce the concentration of OH^– ions

(d) to increase concentration of OH^– ions

Answer-(c)

Question-What is the H⁺ ion concentration of a solution prepared by dissolving 4 g of NaOH (Atomic weight of Na = 23 amu) in 1000 ml?

(a) 10^–10 M

(b) 10^–4 M

(c) 10^–1 M

(d) 10^–13 M

Answer-(d)

Question-Calculate the pOH of a solution at 25°C that contains 1× 10^{– 10} M of hydronium ions, i.e. H₃O⁺.

(a) 4.000

(b) 9.0000

(c) 1.000

(d) 7.000

Answer-(a)

Question-How many litres of water must be added to 1 litre an aqueous solution of HCl with a pH of 1 to create an aqueous solution with pH of 2 ?

(a) 0.1 L

(b) 0.9 L

(c) 2.0 L

(d) 9.0 L

Answer-(d)

Question-Which solution has pH equal to 10 ?

(a) 10^–4 M KOH

(b) 10^–10 M KOH

(c) 10^–10 M HCl

(d) 10^–4 M HCl

Answer-(a)

Question-The pH value of a 10 M solution of HCl is

(a) less than 0

(b) equal to 0

(c) equal to 1

(d) equal to 2

Answer-(a)

Question-Calculate the pH of a solution obtained by diluting 1 mL of 0.10 M weak monoacidic base to 100 mL at constant temperature if Kb of the base is 1 × 10^–5 ?

(a) 8

(b) 9

(c) 10

(d) 11

Answer-(c)

Question-When sodium acetate is added to an aqueous solution of acetic acid :

(a) The pH of the solution decreases

(b) The pH of the solution increases

(c) The pH of the solution remains unchanged

(d) An acid salt is produced

Answer-(b)

Question-The ionisation constant of an acid, Ka, is the measure of strength of an acid. The Ka values of acetic acid, hypochlorous acid and formic acid are 1.74 × 10^–5, 3.0 × 10^{– 8} and 1.8 × 10^–4 respectively. Which of the following orders of pH of 0.1 mol dm^–3 solutions of these acids is correct?

(a) acetic acid > hypochlorous acid > formic acid

(b) hypochlorous acid > acetic acid > formic acid

(c) formic acid > hypochlorous acid > acetic acid

(d) formic acid > acetic acid > hypochlorous acid

Answer-(d)

Question- The first and second dissociation constants of an acid H₂A are 1.0 × 10^–5 and 5.0 × 10^–10 respectively. The overall dissociation constant of the acid will be

(a) 0.2 × 10⁵

(b) 5.0 × 10^–5

(c) 5.0 × 10¹⁵

(d) 5.0 × 10^–15.

Answer-(d)

Question-The solubility of AgI in NaI solution is less than that in pure water because :

(a) the temperature of the solution decreases

(b) solubility product to AgI is less than that of NaI

(c) of common ion effect

(d) AgI forms complex with NaI

Answer-(c)

Question-Calculate the pOH of a solution at 25°C that contains 1× 10^{– 10} M of hydronium ions, i.e. H₃O⁺.

(a) 4.000

(b) 9.0000

(c) 1.000

(d) 7.000

Answer-(a)

Question-Which of the following statements about pH and H+ ion concentration is incorrect?

(a) Addition of one drop of concentrated HCl in NH₄OH solution decreases pH of the solution.

(b) A solution of the mixture of one equivalent of each of CH₃COOH and NaOH has a pH of 7

(c) pH of pure neutral water is not zero

(d) A cold and concentrated H₂SO₄ has lower H⁺ ion concentration than a dilute solution of H₂SO₄

Answer-(b)

Equilibrium MCQ Questions with Answers Class 11 Chemistry

Question- H₂S gas when passed through a solution of cations containing HCl precipitates the cations of second group of qualitative analysis but not those belonging to the fourth group. It is because

(a) presence of HCl decreases the sulphide ion concentration.

(b) solubility product of group II sulphides is more than that of group IV sulphides.

(c) presence of HCl increases the sulphide ion concentration.

(d) sulphides of group IV cations are unstable in HCl.

Answer-(a)

Question-The buffering action of an acidic buffer is maximum when its pH is equal

(a) 5

(b) 7

(c) 1

(d) pKa

Answer-(d)

Question-A buffer solution is prepared in which the concentration of NH3 is 0.30M and the concentration of NH4 + is 0.20 M. If the equilibrium constant, Kb for NH₃ equals 1.8 × 10^–5, what is the pH of this solution ? (log 2.7 = 0.433).

(a) 9.08

(b) 9.43

(c) 11.72

(d) 8.73

Answer-(b)

Question- 100 mL of 0.04 N HCl aqueous solution is mixed with 100 mL of 0.02 N NaOH solution. The pH of the resulting solution is:

(a) 1.0

(b) 1.7

(c) 2.0

(d) 2.3

Answer-(c)

Question- Buffer solutions have constant acidity and alkalinity because

(a) these give unionised acid or base on reaction with added acid or alkali.

(b) acids and alkalies in these solutions are shielded from attack by other ions.

(c) they have large excess of H⁺ or OH^– ions

(d) they have fixed value of pH

Answer-(a)

Question-Equal volumes of three acid solutions of pH 3, 4 and 5 are mixed in a vessel. What will be the H⁺ ion concentration in the mixture ?

(a) 1.11 × 10^–4 M

(b) 3.7 × 10^–4 M

(c) 3.7 × 10^{– 3} M

(d) 1.11× 10^–3 M

Answer-(b)

Question- When a buffer solution, sodium acetate and acetic acid is diluted with water :

(a) Acetate ion concentration increases

(b) H⁺ ion concentration increases

(c) OH^– ion conc. increases

(d) H⁺ ion concentration remains unaltered

Answer-(d)

Question-A salt ‘X’ is dissolved in water of pH = 7. The salt is made resulting solution becomes alkaline in nature. The salt is made

(a) A strong acid and strong base

(b) A strong acid and weak base

(c) A weak acid and weak base

(d) A weak acid and strong base

Answer-(d)

Question-The product of ionic concentration in a saturated solution of an electrolyte at a given temperature is constant and is known as

(a) Ionic product of the electrolyte

(b) Solubility product

(c) Ionization constant

(d) Dissociation constant

Answer-(b)

Question-At 25°C, the solubility product of Mg(OH)₂ is 1.0 × 10^–11.At which pH, will Mg²⁺ ions start precipitating in the form of Mg(OH)2 from a solution of 0.001 M Mg²⁺ ions?

(a) 9

(b) 10

(c) 11

(d) 8

Answer-(b)

Question- pH of a saturated solution of Ba(OH)2 is 12. The value of solubility product (Ksp) of Ba(OH)₂ is :

(a) 3.3 × 10^{– 7}

(b) 5.0 × 10^–7

(c) 4.0 × 10^–6

(d) 5.0 × 10^–6

Answer-(b)

Question-The pKa of a weak acid (HA) is 4.5. The pOH of an aqueous buffer solution of HA in which 50% of the acid is ionized is

(a) 7.0

(b) 4.5

(c) 2.5

(d) 9.5

Answer-(d)

Question-Aqueous solution of ferric chloride is acidic due to

(a) ionization

(b) polarization

(c) dissociation

(d) hydrolysis

Answer-(d)

Question-Why only As⁺³ gets precipitated as As₂S₃ and not Zn⁺² as ZnS when H2S is passed through an acidic solution containing As⁺³ and Zn⁺²?

(a) Solubility product of As₂S₃ is less than that of ZnS

(b) Enough As⁺³ are present in acidic medium

(c) Zinc salt does not ionise in acidic medium

(d) Solubility product changes in presence of an acid

Answer-(a)

Question-The pH of 10^–10 M NaOH solution is nearest to:

(a) 6

(b) – 10

(c) 4

(d) 7

Answer-(d)

Question-The pKa of a weak acid, HA, is 4.80. The pKb of a weak base, BOH, is 4.78. The pH of an aqueous solution of the correspondng salt, BA, will be

(a) 9.58

(b) 4.79

(c) 7.01

(d) 9.22

Answer-(c)

Question-At 100°C the Kw of water is 55 times its value at 25°C. What will be the pH of neutral solution? (log 55 = 1.74)

(a) 6.13

(b) 7.00

(c) 7.87

(d) 5.13

Answer-(a)