JEE Chemistry Equilibrium MCQs Set 03

Question. Which of the following statements about pH and H+ ion concentration is incorrect?
(a) A solution of the mixture of one equivalent of each of CH3COOH and NaOH has a pH of 7
(b) pH of pure neutral water is not zero
(c) Addition of one drop of concentrated HCl in NH4OH solution decreases pH of the solution
(d) None of these

Answer: A

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. 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 weak acid and strong base
(b) A weak acid and weak base
(c) A strong acid and weak base
(d) A strong acid and strong base

Answer: A

Question. Aqueous solution of ferric chloride is acidic due to
(a) hydrolysis
(b) polarization
(c) ionization
(d) dissociation

Answer: A

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) 9.5
(b) 4.5
(c) 7.0
(d) 2.5

Answer: A

Question. Which of the following pairs constitutes a buffer?
(a) HNO2 and NaNO2
(b) HNO3 and NH4NO3
(c) NaOH and NaCl
(d) HCl and KCl

Answer: A

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. The buffering action of an acidic buffer is maximum when its pH is equal
(a) pKa
(b) 7
(c) 5
(d) 1

Answer: A

Question. When a buffer solution, sodium acetate and acetic acid is diluted with water
(a) H+ ion concentration remains unaltered
(b) OH– ion conc. increases
(c) H+ ion concentration increases
(d) Acetate ion concentration increases

Answer: A

Question. The product of ionic concentration in a saturated solution of an electrolyte at a given temperature is constant and is known as
(a) Solubility product
(b) Ionic product of the electrolyte
(c) Ionization constant
(d) Dissociation constant

Answer: A

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) 10
(b) 8
(c) 9
(d) 11

Answer: A

Question. pH of a saturated solution of Ba(OH)2 is 12. The value of solubility product (Ksp) of Ba(OH)2 is
(a) 5.0 × 10–7
(b) 5.0 × 10–6
(c) 3.3 × 10– 7
(d) 4.0 × 10–6

Answer: A

Question. Solubility product of silver bromide is 5.0 × 10–13. The quantity of potassium bromide (molar mass taken as 120 g mol–1) to be added to 1 litre of 0.05 M solution of silver nitrate to start the precipitation of AgBr is
(a) 1.2 × 10–9 g
(b) 5.0 × 10–8 g
(c) 1.2 × 10–10 g
(d) 6.2 × 10–5 g

Answer: A