JEE Chemistry Equilibrium MCQs Set 02

Question.  Which one of the following information can be obtained on the basis of Le Chatelier principle?
(a) Shift in equilibrium position on changing value of a constraint
(b) Equilibrium constant of a chemical reaction
(c) Entropy change in a reaction
(d) Dissociation constant of a weak acid

Answer: A

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 an equilibrium reaction if temperature increases
(a) any of the above
(b) no effect
(c) equilibrium constant decreases
(d) equilibrium constant increases

Answer: A

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. 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) remains unchanged
(b) increases
(c) decreases
(d) equilibrium is disturbed

Answer: A

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) (i), (ii) and (iii)
(b) Only (i) 
(c) (i) and (ii)
(d) (ii) and (iii)

Answer: A

Question.  Which of the following is/are electrolytes?
(i) Sugar solution (ii) Sodium chloride
(iii) Acetic acid      (iv) Starch solution
(a) (ii) and (iii)
(b) (i) and (iv)
(c) (ii) and (iv)
(d) (i) and (iii)

Answer: A

Question. The geometry of hydronium ion is
(a) trigonal pyramidal
(b) tetrahedral
(c) linear
(d) trigonal planer

Answer: A

Question. Which of the following statements are correct regarding Arrhenius theory of acid and base?
(a) Both
(b) This theory could not explain the basicity of substances like ammonia which do not possess a hydroxyl group
(c) This theory was applicable to all solutions
(d) This theory was applicable to only aqueous solutions

Answer: A

Question. Would gaseous HCl be considered as an Arrhenius acid ?
(a) No
(b) Not known
(c) Gaseous HCl does not exist
(d) Yes

Answer: A

Question.  A base, as defined by Bronsted theory, is a substance which can
(a) accept protons
(b) gain a pair of electrons
(c) donate protons
(d) lose a pair of electrons

Answer: A

Question. BF₃ is an acid according to
(a) Lewis Concept
(b) Arrhenius concept
(c) Bronsted-Lowry concept
(d) None of these

Answer: A

Question. Among boron trifluoride, stannic chloride and stannous chloride, Lewis acid is represented by
(a) boron trifluoride and stannous chloride
(b) only boron trifluoride
(c) boron trifluoride and stannic chloride
(d) only stannic chloride

Answer: A

Question. Which one of the following molecular hydrides acts as a Lewis acid?
(a) B₂H₆
(b) NH₃
(c) H₂O
(d) CH₄

Answer: A

Question. Which of these is least likely to act as Lewis base?
(a) BF₃
(b) CO
(c) F^–
(d) PF₃

Answer: A

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

Answer: A

Question. The value of the ionic product of water
(a) depends on temperature
(b) changes by adding acid or alkali
(c) always remains constant
(d) depends on volume of water

Answer: A

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) neutral
(c) acidic
(d) None of these

Answer: A

Question.  pH scale was introduced by
(a) Sorensen
(b) Lowry
(c) Lewis
(d) Arrhenius

Answer: A

Question. The pH of a 10^–3 M HCl solution at 25°C if it is diluted 1000 times, will be –
(a) 5.98
(b) 6.02
(c) zero
(d) 3

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) 9.0 L
(b) 0.9 L
(c) 0.1 L
(d) 2.0 L

Answer: A

Question. What is the approximate pH of a 1 × 10^–3 M NaOH solution?
(a) 11
(b) 1 × 10^–11
(c) 3
(d) 7

Answer: A

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) 1.000
(c) 7.000
(d) 9.0000

Answer: A

Question. The pH value of a 10 M solution of HCl is
(a) less than 0
(b) equal to 1
(c) equal to 0
(d) equal to 2

Answer: A

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^–13 M
(b) 10^–4 M
(c) 10^–10 M
(d) 10^–1 M

Answer: A

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) 1.000
(c) 9.0000
(d) 7.000

Answer: A

Question. The pH of 0.005 molar solution of H₂SO₄ is approximately:
(a) 2
(b) 0.010
(c) 1
(d) 0.005

Answer: A

Question. Which solution has pH equal to 10 ?
(a) 10^–4 M KOH
(b) 10^–10 M HCl
(c) 10^–10 M KOH
(d) 10^–4 M HCl

Answer: A

Question. A weak acid, HA, has a K_a 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) 0.100%
(c) 99.9%
(d) 99.0%

Answer: A

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) 0.2
(b) 0.25
(c) 2.0
(d) 0.5

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 K_b of the base is 1 × 10^–5 ?
(a) 10
(b) 8
(c) 9
(d) 11

Answer: A

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) 5.0 × 10^–15.
(b) 5.0 × 10^–5
(c) 0.2 × 10⁵
(d) 5.0 × 10¹⁵

Answer: A

Question. Equimolar solutions of HF, HCOOH and HCN at 298 K have the values of K_a as 6.8 × 10^–4 and 4.8 × 10^–9 respectively. What is the observed trend of dissociation constants in successive stages ?
(a) HF > HCOOH > HCN
(b) HCOOH > HCN > HF
(c) HF > HCN > HCOOH
(d) HCN > HF > HCOOH

Answer: A

Question. Which of the following pK_a value represents the strongest acid ?
(a) 10^–8
(b) 10^–2
(c) 10^–4
(d) 10^–5

Answer: A

Question. The dissociation constant of two acids HA₁ and HA₂ are 3.14 × 10_{– 4} and 1.96 × 10_{– 5} respectively. The relative strength of the acids will be approximately
(a) 4 : 1
(b) 16 : 1
(c) 1 : 4
(d) 1 : 16

Answer: A

Question. At 298K a 0.1 M CH₃COOH solution is 1.34% ionized. The ionization constant K_a for acetic acid will be
(a) 1.82 × 10^{– 5}
(b) 0.182 × 10 ^–5
(c) 18.2 × 10 ^–5
(d) None of these

Answer: A

Question. Cationic hydrolysis gives the following solution
(a) acidic
(b) basic
(c) amphoteric
(d) neutral

Answer: A

Question. In qualitative analysis, in III group NH₄Cl is added before NH₄OH because
(a) to reduce the concentration of OH^– ions
(b) to increase concentration of OH^– ions
(c) to increase concentration of Cl^– ions
(d) None of these

Answer: A

Question. The solubility of AgI in NaI solution is less than that in pure water because
(a) of common ion effect
(b) AgI forms complex with NaI
(c) solubility product to AgI is less than that of NaI
(d) None of these

Answer: A

Question. When sodium acetate is added to an aqueous solution of acetic acid
(a) The pH of the solution increases
(b) The pH of the solution decreases
(c) An acid salt is produced

Answer: A