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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 52)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 12) 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

The reaction will proceed from right to left if

(a) Q = Kc.

(b) Q c

(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 nV) 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 2S

(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 12) N2 + (frac 32) 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 14)


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

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)
3. Table salt solution (iii) >7
4. Thomas slag solution (iv) Nearly 7
Answer

Answer:

Column I Column II
1. Lunar caustic (ii)
2. Washing soda solution (iii) >7
3. Table salt solution (i) 7
4. Thomas slag solution (iv) Nearly 7

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