NCERT Class 11 Chemistry Lab Manual Chemical Equilibrium Ionic Equilibrium

Question. At 298 K, the solubility product of PbCl₂ is 1.0 x 10⁻⁶.
What will be the solubility of PbCl₂ in moles/litre
a. 3 6.3 10× −
b. 3 1.0 10× −
c. 3 3.0 10× −
d. 14 4.6 10× −
Answer : A

Question. The solubility of BaSO₄ in water is 2.33×10^–3 gm/litre. Its solubility product will be (molecular weight of BaSO₄ = 233)
a. 1 x 10⁻⁵
b. 1 x 10⁻¹⁰
c. 1 x 10⁻¹⁵
d. 1 x 10⁻²⁰
Answer : B

Question. Assuming complete dissociation, which of the following aqueous solutions will have the same pH value?
a. 100ml of 0.01 M HCl
b. 100ml of 0.01 M H₂SO₄
c. 50 ml of 0.01 M HCl
d. Mixture of 50 ml of 0.02 M H₂SO₄ and 50 ml of 0.02 M
NaOH
Answer : A. D

Question. Solubility product of a sulphide MS is 3 x 10⁻²⁵ and that of another sulphide NS is 4 x 10⁻⁴⁰ In ammoniacal solution
a. Only NS gets precipitated
b. Only MS gets precipitated
c. No sulphide precipitates
d. Both sulphides precipitate
Answer : D

Question. Which one of the following is most soluble?
a. CuS (K_sp = 8 x 10⁻³⁷)
b. MnS (K_sp = 7 x 10⁻¹⁶)
c. Bi₂S₂ (K_sp = 1 x 10⁻⁷⁰)
d. Ag₂S (K_sp = 6 x 10⁻⁵¹)
Answer : B

Question. The solubility product of a salt having general formula MX₂, in water is: 4 10⁻¹² The concentration of M²⁺ ions in the aqueous solution of the salt is
a. 2.0 x 10 M⁻⁶
b. 1.0 x 10 M⁻⁴
c. 1.6 x 10 M⁻⁴
d. 4.0 x 10 M⁻¹⁰
Answer : B

Question. The addition of HCl will not suppress the ionization of
a. Acetic acid
b. Benzoic acid
c. H₂S
d. Sulphuric acid
Answer : D

Question. Why pure NaCl is precipitated when HCl gas is passed in a saturated solution of NaCl:
a. Impurities dissolves in HCl
b. The value of [Na⁺] and[Cl⁻] becomes smaller than sp K_sp of NaCl
c. The value of [Na⁺] and [Cl⁻] becomes greater than sp K_sp of NaCl
d. HCl dissolves in the water
Answer : C

Question. If the solubility product K_sp of a sparingly soluble salt MX₂ at 25°C is 1.0×10^–11, the solubility of the salt in mole litre^–1 at this temperature will be
a. 2.46×10¹⁴
b. 1.36x10⁻⁴
c. 2.60x10⁻⁷
d. 1.20x10⁻¹⁰
Answer : B

Question. An acid-base indicator has the acid form of the indicator is red and the form is blue. Then:
a. pH is 4.04 when indicator is 75% red
b. pH is 5.00 when indicator is 75% blue.
c. pH is 5.00 when indicator is 75% red.
d. pH is 4.05 when indicator is 75% blue.
Answer : A, B

Question. The colour of an electrolyte solution depends on:
a. The nature of the anion
b. The nature of the cation
c. The nature of both the ions
d. The nature of the solvent
Answer : C

Question. The compound whose 0.1M solution is basic is:
a. Ammonium acetate
b. Calcium carbonate
c. Ammonium sulphate
d. Sodium acetate
Answer : D

Question. Assuming complete dissociation, which of the following aqueous solutions will have the same pH value:
a. 100ml of 0.01 M HCl
b. 100ml of 0.01 M H₂SO₄
c. 50ml of 0.01 M HCl
d. Mixture of 50ml of 0.02 M H₂SO₄ and 50ml of 0.02 M NaOH
Answer : A, D

Question. Which of the following will not function as a buffer solution?
a. NaCl and NaOH
b. NaOH and NH₄OH
c. CH₃COONH₄ and HCl
d. Borax and boric acid
Answer : A, B, C

Question. The following reaction is known to occur in the body CO₂ + H₂O ⇌ H₂CO₃ ⇌ H⁺ + HCO₃⁻ If CO₂ escapes from the system:
a. pH will decrease
b. Hydrogen ion concentration will decrease
c. H₂CO₃ concentration will be unaltered
d. The forward reaction will be promoted
Answer : B

Question. Correct statement is:
a. NH₄ Cl gives alkaline solution in water
b. NH₃ COONa gives acidic solution in water
c. NH₃ COOH is a weak acid
d. NH₄ OH is a strong base
Answer : C

Question. At 90^oC pure water has 6 [H₃O⁺] = 10^-6 M, the value of K_w at this temperature will be:
a. 6 10−
b. 12 10−
c. 14 10−
d. 8 10−
Answer : B

Question. K_sp value of Al(OH)₃ and Zn(OH)₂ are 8.5×10^–23 and 1.8×10^–14 respectively. If NH₄ OH is added in a solution of Al³⁺ and Zn²⁺, which will precipitate earlier:
a. Al (OH)₃
b. Zn (OH)₂
c. Both together
d. None
Answer : A

Question. The K_sp of Mg(OH)₂ is 1×10^–12, 0.01 M Mg (OH₂) will precipitate at the limiting pH:
a. 3
b. 9
c. 5
d. 8
Answer : B

Assertion and Reason

Note: Read the Assertion (A) and Reason (R) carefully to mark the correct option out of the options given below:
a. If both assertion and reason are true and the reason is the correct explanation of the assertion.
b. If both assertion and reason are true but reason is not the correct explanation of the assertion.
c. If assertion is true but reason is false.
d. If the assertion and reason both are false.
e. If assertion is false but reason is true.

Question. Assertion: CHCl₃ is more acidic than CHF₃.
Reason: The conjugate base of CHCl₃ is more stable than CHF₃.
Answer : A

Question. Assertion: Ionic reactions are not instantaneous.
Reason: Oppositely charged ions exert strong forces.
Answer : C

Question. Assertion: A solution of FeCl₃ in water produce brown precipitate on standing.
Reason: Hydrolysis of FeCl₃takes place in water
Answer : A

Question. Assertion: BaCO₃ is more soluble in NHO₃ than in plain water.
Reason: Carbonate is a weak base and reacts with the H+ from the strong acid, casuing the barium salt to dissociate.
Answer : A

Question. Assertion: The amino acid glycine predominantly exists in the form of ^⊕NH₃CH₂COO^⊙ .
Reason: The conjugate acid of glycine is NH₂CH₂COO^⊙ .
Answer : C

Question. Assertion: pH of hydrochloric acid solution is less than that of acetic acid solution of the same concentration.
Reason: In equimolar solutions, the number of titrable protons present in hydrochloric acid is less than that persent in acetic acid.
Answer : C

Question. Assertion: A ionic product is used from any types of electrolytes whereas solubility product is applicable only to sparingly soluble salts.
Reason: Ionic product is defined at any stage of the raction whereas solubility product is only appicable to the saturation stage.
Answer : B

Question. Assertion: Addition of silver ions to a mixture of aqueous sodium chloride and sodium bromide solution will first precipitate AgBr rather than AgCl.
Reason: Ksp of AgCl < Ksp of AgBr.
Answer : C

Question. Assertion: The pH of an aqueous solution of CH₃COOH remains unchanged on the addition of CH₃COONa.
Reason: The ionization of CH₃COOH is suppressed by the addition of CH₃COONa.
Answer : D

Comprehension Based

Paragraph –I

In qualitative analysis, cations of group II as group II as well as group IV both are precipitated in the form of sulphides. Due to low value of Ksp of group II sulphides, group reagent is H₂S in the presence of dil. HCl and due to high value of Ksp of group IV sulphides, group reagent is H₂S in the presence of NH₄OH and NH4Cl. In solution containing 0.1M each of Sn2+, Cd²⁺, andNi²⁺ ions, H₂S gas is passed. Ksp of SnS = 8×10^–29, Ksp of CdS = 15 10^–28, Ksp of NiS = 3×10^–21, K₁ of H₂S=1×10^–7, K₂ of H₂S = 1×10^–14

Question. If H₂S is passed into the above mixture in the presence of HCl, which ion will be precipitated first?
a. SnS
b. CdS
c. NiS
d. SnS and CdS
Answer : C

Question. At what value of pH, NiS will start to precipitate?
a. 12.76
b. 7
c. 1.24
d. 4
Answer : C

Question. Which of the following sulphides is more soluble in pure water?
a. Cds
b. NiS
c. SnS
d. Equal solubility for all
Answer : A

Question. If 0.1 M HCl is mixed in the solution containing only 0.1 MCd²⁺ ions and saturated with H₂S, then [Cd²⁺] remaining in the solution after CdS stops to precipitate is:
a. 10^–8
b. 8.2 × 10^–9
c. 5.6 × 10^–6
d. 5.6 × 10^–10
Answer : A

Paragraph –II

Acid rain takes place due to combination of acidic oxides with water and it is an environmental concern all over the world. Assuming rain water is uncontaminated with HNO₃ or H₂CO₃ and is in equilibrium with 1.25×10^–4 atm CO₂. The Henry’s law constant (K_H) is 1.25×10⁶ torr. K_a1 of H₂CO₃ = 4.3×10^–7. Given K_fCuCl^⊕ 1.0(K_f = is formation constant of CuCl^⊕)

Question. What is the pH of natural rain water?
a. 5.64
b. 7.00
c. 5.87
d. 7.40
Answer : C

Question. If content is the atmosphere is 0.64 ppm by volume, pH of rain water is (assume 100% ionization of acid rain as monobasic acid).
a. 4.0
b. 5.0
c. 6.0
d. 7.0
Answer : B

Paragraph –III

In acid-base titration reacts rapidly to neutralize each other. Equivalence point is point at which the acid and the base (or oxidising agent and reducing agent) have been added in equivalent quantities. The end point is the point at which the titration stops. Since the purpose of the indicator is to stop the titration close to the point at which the acid and base were added in equivalent quantities, it is important that the equivalent point and the end point be as close as possible. The indicator must change colour at a pH close to that of a solution of the salt of the acid and base. Significantly, the pH changes most rapidly neat the equivalence point. The exact shape of a titration curve depends on K_a and K_b of acid base.

Question. The following curve represents titration curve of HCl against KOH. The pH at equivalent point is. Examine the titration curve below and answer the question:
a. 3
b. 6
c. 7
d. 8
Answer : C

Question. The curve represents the titration of?
a. CsOH by HBr
b. HCl by NaOH
c. HCl by KOH
d. NH₃ by HNO₃
Answer : A

Question. The suitable indicator for the titration is?
a. Methyl orange
b. Bromothymol
c. Methyl red
d. All of these
Answer : D

Question. The pH at equivalence point is?
a. 2
b. 3
c. 7
d. 11
Answer : C

Question. Which of the following curves indicates the titration of a weak diprotic acid by KOH by equivalent strength?

Answer : A

Integer

Question. How many of the conbinations of reactants in (8) above will react until more than 98% of the limiting quantity is used up?
Answer : 8

Question. The dissociation constant of a substituted benzoic acid at 25°C is 1.1 × 10^–1. Find the pH of a 0.01 M solution of its sodium salt.
Answer : 8

Question. Among the following, find the total number of compounds whose aqueous solution turns red litmus paper blue KCN, K₂SO₄, (NH₄)₂, C₂O₄, NaCl, Zn(NO₃)₂, FeCl₂, K₂CO₃, NH₄NO₂, LiCN.
Answer : 3

Question. Find the total number of diprotic acids among the following.
H₃PO₄, H₂SO₄, H₃ PO₃, H₂CO₃, H₂S₂O₇, H₃BO₃, H₃PO₂, H₂CrO4, H₂SO₃
Answer : 6

Question. In 1 L saturated solution of AgCl(Ksp of AgCl) =1.6×10^–10), 0.1 mol of CuCl (K_sp CuCl = 1.0×10^–6) is added. The resultant concentration of Ag+ in the solution is 1.6 ×10^–x. Calculate the value of x.
Answer : 7

Question. Match the statement of Column I with those in Column II:

a. A→3,4, B→1, C→2,4, D→2,4
b. A→3,4, B→1, C→2,4, D→2,2
c. A→4,4, B→2, C→1,4, D→2,4
d. A→2,4, B→1, C→2,4, D→2,3
Answer : A

Question. Match the statement of Column I with those in Column II:

a. A→1, B→2, C→3, D→1,4,2
b. A→1, B→2, C→2, D→1,4,3
c. A→1, B→1, C→2, D→1,3,2
d. A→1, B→2, C→1, D→1,4,4
Answer : A

                                CHEMICAL EQUILIBRIUM (IONIC EQUILIBRIUM IN SOLUTION)

CHEMICAL Reactions  can be classified into two categories; namely reversible and irreversible reactions. Reversible reactions take place in the same reaction vessel and can proceed in the forward and backward direction simultaneously under the same conditions of temperature and pressure. Further in the case of reversible reactions a state is reached, when the rate of the forward reaction becomes equal to the rate of the reverse reaction and it appears as though the reaction has come to a  stand  still. This state is referred to as the state of dynamic equilibrium. Consider the following simple reversible reaction at the given temperature, T.

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