NEET Chemistry Equilibrium MCQs Set 03

Question:  The hydrogen ion concentration of a 10^–8 M HCl aqueous solution at 298 K (K_w= 10^–14) is

• a) 1.0 × 10^–6 M 
• b) 1.0525 × 10^–7 M 
• c) 9.525 × 10^–8 M
• d) 1.0 × 10^–8 M

Answer:  1.0525 × 10^–7 M 

Question:  At 25°C, the dissociation constant of a base, BOH, is 1.0 × 10^–12. The concentration of hydroxyl ions in 0.01M aqueous solution of the base would be 

• a) 2.0 × 10^–6 mol L^–1 
• b) 1.0 × 10^–5 mol L^–1
• c) 1.0 × 10^–6 mol L^–1 
• d) 1.0 × 10^–7 mol L^–1

Answer:  1.0 × 10^–7 mol L^–1

Question:  Equilibrium constants K₁ and K₂ for the following equilibria:

are related as

• a)

  

• b) K₂= K₁2
• c)

  

• d)

  

Answer:

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) Presence of HCl increases the sulphide ion concentration
• c) Solubility product of group II sulphides is more than that of group IV sulphides
• d) Sulphides of group IV cations are unstable in HCl

Answer: Presence of HCl decreases the sulphide ion concentration

Question:  The dissociation constant of a weak acid is 1 × 10^–4. In order of prepare a buffer solution with a pH = 5 the [Salt]/[Acid] ratio should be

• a) 1 : 10
• b) 4 : 5
• c) 10 : 1
• d) 5 : 4

Answer: 10 : 1

Question: Which one of the following is not acid-base conjugate pair?

• a) HONO, NO₂^–
• b) CH₃NH₃⁺, CH₃NH₂
• c) C₆H₅– COOH, C₆H₅COO^– 
• d) H₃O⁺, OH^–

Answer:  H₃O⁺, OH^–

Question:

For the reactions

The relation between K₁, K₂, K₃ is

• a) K₃= K₁+ K₂ 
• b) K₃= K₁K₂
• c) K₃= K₁/K₂  
• d) K₃= K₂/K₁

Answer: K₃= K₁K₂

Question:  Given exothermic reaction

Which one of the following will decrease the equilibrium concentration of  ?

• a) Addition of HCl
• b)

  

• c) The solution is diluted with water
• d) The temperature is increased

Answer: The solution is diluted with water

Question: For preparing a buffer solution of pH = 7.0, which buffer system you will choose?

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question:  For a chemical reaction of the type

Equilibrium constant for the reaction

• a) 25
• b) 50
• c) 2500
• d) 4 × 10^–4

Answer: 2500 

More Questions.................................

Question:  A solution is 0.1 M with respect to Ag⁺, Ca²⁺, Mg²⁺ and Al³⁺ which will precipitate at lowest concentration of

when solution of Na₃PO₄ is added ?

• a) Ag₃PO₄(K_sp= 1 × 10^–6) 
• b) Ca₃(PO₄)₂(K_sp= 1 × 10^–33)
• c) Mg₃(PO₄)₂(K_sp= 1 × 10^–24)
• d) AlPO₄(K_sp= 1 × 10^–20)

Answer:  AlPO₄(K_sp= 1 × 10^–20)

Question:  At 100°C the K_w 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: 6.13

Question: Which one of the following species acts only as a base?

• a) H₂S
• b) HS^–
• c) S^2– 
• d) H₂O

Answer:  S^2– 

Question: Which one of the following is most soluble?

• a) Bi₂S₃(K_sp= 1 × 10^–70) 
• b) Ag₂S (K_sp= 6 × 10^–51)
• c) CuS (K_sp= 8 × 10^–37) 
• d) MnS (K_sp= 7 × 10^–16)

Answer:  MnS (K_sp= 7 × 10^–16)

Question: The pH value of blood does not appreciably change by a small addition of an acid or a base, because the blood

• a) Can be easily coagulated
• b) Contains iron as a part of the molecule
• c) Is a body fluid
• d) Contains serum protein which acts as buffer

Answer: Contains serum protein which acts as buffer

Question:  The pH value of 10^–7 M solution HCl is

• a) Equal to 1
• b) Equal to 2
• c) Less than 7
• d) Equal to 0

Answer: Less than 7

Question:  At 80°C, distilled water has [H₃O⁺] concentration equal to 1 × 10^–6 mole/litre. The value of K_w at this temperature will be

• a) 1 × 10^–12 
• b) 1 × 10^–15
• c) 1 × 10^–6  
• d) 1 × 10^–9

Answer:  1 × 10^–12 

Question:  Standard state Gibb’s free energy change for isomerization reaction 

 is pentene is –3.67 kJ/mol at 400 K. If more trans-2-pentene is added to the reaction vessel, then

• a) Equilibrium remains unaffected
• b) Equilibrium is shifted in the forward direction
• c) More cis-2-pentene is formed
• d) Additional trans-2-pentene is formed

Answer: More cis-2-pentene is formed

Question:  The ionic product of water at 25°C is 10^–14. Its ionic product at 90°C will be

• a) 1 × 10^–14
• b) 1 × 10^–16
• c) 1 × 10^–20 
• d) 1 × 10^–12

Answer:  1 × 10^–12

Question:  If α is degree of dissociation, then the total number of moles for the reaction starting with 1 mole of HI 2HI =H₂+ I₂ will be

• a) 1
• b) 1 – α 
• c) 2
• d) 2 – α

Answer: 1

Question: Which of the following is not a Lewis acid?

• a) SiF₄ 
• b) C₂H₄
• c) BF₃  
• d) FeCl₃

Answer: C₂H₄

Question:  The solubility product of CuS, Ag₂S and HgS are 10^–31, 10^–44, 10^–54 respectively. The solubilities of these sulphides are in the order

• a) HgS > Ag₂S > CuS 
• b) CuS > Ag₂S > HgS
• c) Ag₂S > CuS > HgS
• d) AgS > HgS > CuS

Answer:  Ag₂S > CuS > HgS

Question:  The concentration of [H⁺] and concentration of [OH^– ] of a 0.1 M aqueous solution of 2% ionised weak acid is [ionic product of water = 1 × 10^–14]

• a) 2 × 10^–3 M and 5 × 10^–12 M 
• b) 1 × 10^–3 M and 3 × 10^–11 M
• c) 0.02 × 10^–3 M and 5 × 10^–11 M 
• d) 3 × 10^–2 M and 4 × 10^–13 M

Answer:  2 × 10^–3 M and 5 × 10^–12 M 

Question:  The solubility of a saturated solution of calcium fluoride is 2 × 10^–4 moles per litre. Its solubility product is

• a) 22 × 10^–11
• b) 14 × 10^–4
• c) 2 × 10^–2 
• d) 32 × 10^–12

Answer:  32 × 10^–12

Question:  Conjugate acid of NH₂^–

• a) NH₄OH
• b) NH₄⁺ 
• c) NH^2– 
• d) NH₃

Answer:  NH₃

Question:  The values of K_sp of CaCO₃ and CaC₂O₄ are 4.7 × 10^–9 and 1.3 × 10^–9 respectively at 25°C. If the mixture of these two is washed with water, what is the concentration of Ca²⁺ ions in water?

• a) 7.746 × 10^–5 M
• b) 5.831 × 10^–5 M 
• c) 6.856 × 10^–5 M
• d) 3.606 × 10^–5 M

Answer:  7.746 × 10^–5 M

Question: Which statement is wrong about pH?

• a) pH of pure water is not zero
• b) Adding 1 N, solution of CH₃COOH and 1 N NaOH pH will be seven
• c) pH of dilute and hot H₂SO₄ is less than 7
• d) Mixing solution of CH₃COOH and HCl, pH will be less than 7

Answer:  Adding 1 N, solution of CH₃COOH and 1 N NaOH pH will be seven

Question:  Solution of 0.1 N NH₄OH and 0.1 N NH₄Cl has pH 9.25. Then find out pK_b of NH₄OH

• a) 9.25
• b) 4.75
• c) 3.75
• d) 8.25

Answer: 4.75

Question:  Ionisation constant of CH₃COOH is 1.7 × 10^–5 and concentration of H⁺ ions is 3.4 × 10^–4. Then find out initial concentration of CH₃COOH molecules

• a) 3.4 × 10^–4
• b) 3.4 × 10^–3
• c) 6.8 × 10^–4 
• d) 6.8 × 10^–3

Answer:  6.8 × 10^–3

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

• a) (CH₃)₃N
• b) (CH₃)₃B 
• c) (CH₃)₂O 
• d) (CH₃)₃P

Answer:  (CH₃)₃B