ECAT Pre Engineering Chemistry Chapter 8 MCQ Test With Answer

• Introduction of an inert gas at constant volume A
• Introduction of PCl₃(g) at constant B
• Introduction of PCl₅(g) at constant volume C
• Introduction of Cl₂at constant volume D

I a chemical reaction equilibrium is said to have been established when :

• Rate of opposing reactions are equal. A
• Rate constants of opposing reactions are equal. B
• Opposing reactions stop. C
• Concentration of reactants and products are equal D

N₂O₄⇌ 2NO₂

For the above reaction, which of the Following expression of K_c correct :

• Kc = [ N₂O₄]/[ NO ₂]²

  A

• Kc = [ N₂O₄]/ [NO ₂]

  B

• Kc = [ N₂O]²/[ N₂O ₄]

  C

• Kc = [ N₂O₄]/[ N O ₂]

  D

In an exothermic reaction, a 10° rise in temperature will

• Decrease the value of equilibrium constant A
• Double the value of K_c B
• Not produce any change in K_c C
• Produce some increase in K_c D

A chemical reaction is in equilibrium when

• Formation of product is minimum A
• Reactants are completely transformed into products B
• Rates of forward and backward reactions are equal C
• Equal amounts of reactants and products are present D

2SO₂+ O₂⇌2SO₂H= 188KJ mole^-1

Which statement about following equilibrium is correct :

• The value ofK_pfalls with arise in temperature.

  A

• The value ofK_pis equal tok_c.

  B

• The value ofK_pfalls with the increase pressure.

  C

• Adding V₂O₅catalyst increase the equilibrium yield of Sulphur trioxide.

  D

• Complete conversion of A to B has taken place A
• Conversion of A to B is only 50% complete B
• Only 10% conversion of A to B has taken place C
• The rate of transformation of A to B is just equal to rate of transformation of B to A in the system D

Whenever a week base is dissolved in water, it give its conjugate acid. similarly a weak acid in water produces its conjugate base. This conjugate acid-base pair concept is stated by

• Law of mass action A
• Le-charlier's principle B
• Common ion effect C
• Lowery Bronsted concept D

The rate of reaction :

• Remain same as reaction proceeds. A
• May decrease or increase as reaction proceeds . B
• Increase as reaction proceeds. C
• Decreases as reaction proceeds. D

pH and pKa of the buffer are related by Henderson equation which is

• 
  A
• 
  B
• 
  C
• 
  D

• K_p> K_c A
• K_c> K_p B
• K_p= K_c C
• None of these D

At certain temperature, 50% of HI is dissociated into H₂and I₂the equilibrium constant is

• 1.0 A
• 3.0 B
• 0.5 C
• 0.25 D

• The value of K_pfalls with a rise in temperature A
• The value of K_pfalls with increasing pressure B
• Adding V₂O₅catalyst increase the equilibrium yield of sulphur trioxide equilibrium yield of sulphur trioxide C
• The value of K_pis equal to K_c D

K_bfor NH₄OH is 1.81 x 10^-5, then K_avalue of its conjugate base is

• 1.81 x 10⁺⁵ A
• 1.81 x 10^-9 B
• 5.5 x 10^-9 C
• 5.5 x 10^-10 D

• 4 mole per dm³ A
• 2 mole per dm³ B
• 0.33 mole per dm³ C
• 0.67 mole per dm³ D

When rate of forward reaction is equal to rate of backward reaction, then the equilibrium established is called

• Chemical equilibrium A
• Static equilibrium B
• Dynamic equilibrium C
• None of these D

1 mol of N₂O₄ was decomposed according to given equation in 1dm₃ container. At equilibrium x mole of N₂O₄ have dissociated. What is the value of K_C:

• 2x/(1-x)²

  A

• 4x²/(1-x)

  B

• 4x/(1-x)

  C

• 2x/(1-x)

  D

Buffers having pH less than 7 are made

• Mixture of weak acid + salt of it with strong base A
• Mixture of weak acid + salt of it with weak base B
• Mixture of weak base + salt of it with strong acid C
• Mixture of weak base + salt of it with weak base D

For what value ofK_{c almost forward reaction is complete :}

• K_{c =} 10³⁰

  A

• K_{c =} 10^-30

  B

• K_{c =} 0

  C

• K_{c =} 1

  D

Law of mass action was given by :

• Guldberg and Waage. A
• Berkeley and Hartly. B
• Ramsay and Reyleigh. C
• Berthelot. D

The solubility product of AgCl is 2.0 x 10^-10mol²dm^-6The maximum concentration of Ag⁺ions in the solution is

• 2.0 x 10^-10mol dm^-3 A
• 1.41 x 10^-5mol dm^-3 B
• 1.0 x 10^-10mol dm^-3 C
• 4.0 x 10^-20mol dm^-3 D

For which system does the equilibrium constant, KC has units of concentration

• 
  A
• 
  B
• 
  C
• 
  D

• High temperature A
• Low temperature B
• Low pressure C
• High pressure D

• 
  A
• 
  B
• 
  C
• 
  D

Which one of the following is not a buffer

• H₂CO₃+ NaHCO₃solution A
• H₃PO₄+ NaH₂PO₄solution B
• Hl + Nal solution C
• NH₄OH + NH₄CI solution D

Chemical equilibrium involving reactants and products in more than one phase is called

• Static A
• Dynamic B
• Homogeneous C
• Heterogeneous D

• 
  A
• 
  B
• 
  C
• 
  D

The best buffer is prepared when molar concentrations of the salt and acid are equal, then its pH and pKa value are related

• pH = pKa A
• pH < pKa B
• pH > pKa C
• pH x pKa = 14 D

• Reversible reaction A
• Irreversible reaction B
• Spontaneous reaction C
• None of these D

• Shift reaction toward forward direction A
• Shift reaction backward B
• Lower the value of K_c C
• No change in reaction D