ECAT Pre Engineering Chemistry Chapter 8 MCQ Test With Answer

The rate at which a substance reacts is directly proportional to its active mass and the rate of reaction is directly proportional to the product of the active masses of reacting substances, is called

• Law of conservation of energy A
• Le-Chateliers principle B
• Law of mass action C
• None of these D

Which one of the following is a buffer

• HCI + NaCI solution A
• CH₃COOH + CH₃COONH₄solution B
• H₂SO₄+ CaSO₄solution C
• CH₃COOH + CH₃COONa D

In a reversible chemical reaction having two reactants in equilibrium, if the concentration of the reactants are doubled then the equilibrium constant will

• Also be doubled A
• Be halved B
• Becomes one fourth C
• Remains the same D

• 
  A
• 
  B
• 
  C
• 
  D

Two moles of HI was heated in a sealed tube at 440°C till the equilibrium was reached. HI was found to be 22% decomposed. The equilibrium constant for dissociation is

• 0.282 A
• 0.0796 B
• 0.0199 C
• 1.99 D

Ifk_cof a reaction productis verylarge, it indicates that equilibrium occurs :

• With the help of a catalyst. A
• With no forward reaction. B
• At a low product concentration. C
• At a high product concentration. D

The solubility of KCIO₃salt in water is decreased by adding

• NaCIO₃ A
• NaCI B
• KCIO₄ C
• KCI D

A chemical reaction A---------->B is said to be in equilibrium when :

• Rate of transformation of A to B is equal to B to A. A
• 50% reactant has been changed to B. B
• Conversion of A to B is 50% complete C
• Complete conversion of A to B has taken place. 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

In a reversible reaction, two substances are in equilibrium. If the concentration of each one is reduced to half, the equilibrium constant will be

• Reduced to half of its original value A
• Doubled B
• Same C
• Reduced to one fourth its original value D

strength of an acid can be determined by

• P^ka A
• P^kp B
• P^oH C
• P^kw D

The substance which increases rate of reaction but remains unchanged at the end of reaction is called :

• Catalyst. A
• Indicator. B
• Promoter. C
• Activator. D

An excess of aqueous silver nitrate is added to aqueous barium chloride and precipitate is removed by filtration. What are the main ions in the filtrate

• 
  A
• 
  B
• 
  C
• 
  D

• 
  A
• 
  B
• 
  C
• 
  D

• 0.073 A
• 0.147 B
• 0.05 C
• 0.026 D

H₂ + L₂ ----2Hl

In the above equilibrium system, if the concentration of reactants at 25°C is increased, the value K_C will :

• Remains Constant A
• Increases B
• Cecreases C
• Depends upon nature of reactans D

• Le-chatlier's principle A
• Only adding catalyst B
• Decreasing pressure C
• Decreasing temperature D

The rate of a chemical reaction is directly;y proportional to product of molar concentration of reaction substance it is called :

• Low of conservation of energy. A
• Law of mass action. B
• Rate law . C
• Active mass rule. D

1.1 mol of A is mixed with 2.2 mol of B and the mixture is kept in on litre flask till the equilibrium is reached. At equilibrium, 0.2 mol of C is formed. If the equilibrium reaction is A+2B 2C+D, the value of equilibrium constant is

• 0.002 A
• 0.004 B
• 0.001 C
• 0.003 D

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

A buffer of a 0.09 molar acetic acid and 0.11 molar sodium acetate has pH = 4.83. If 0.01 mole NaOH in 1 dm³of the buffer solution is added, then pH of the buffer becomes

• 4.74 A
• 4.92 B
• 5.0 C
• 4.0 D

Law of mass action was given by :

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

• The value of K_pfalls with rise in temperature A
• The value of K_pfalls with increasing pressure B
• Addition of V₂O₅catalyst increase the concentration of SO₃ C
• The value of K_pis equal to K_c D

• KC = KP A
• Kp = KcRT B
• Kp = kc(RT)^-2 C
• Kp = Kc(RT)^-1 D

K_spvalue for PbSO₄= 1.8 x 10^-8mole²dm^-6. The maximum concentration of Pb⁺⁺ions is

• 1.34 x 10^-4mole dm^-3 A
• 1.8 x 10^-4 B
• 3.6 x 10^-16mole dm^-3 C
• 1.0 x 10^-8mole dm^-3 D

The equilibrium constant in a reversible chemical reaction at a given temperature

• Depends on the initial concentration of the reactants A
• Depends on the concentration of one of the products at equilibrium B
• Does not depend on the initial concentration of rectants C
• It is characteristic of the reaction D

The solubility of PbF₂is 2.6 x 10^-3mole dm^-3 then its solubility product is

• 2.6 x 10^-3 A
• 6.76 x 10^-6 B
• 5.2 x 10^-6 C
• 7.0 x 10^-8 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

• Reaction occurs at STP A
• Reaction is exothermic B
• Reaction is endothermic C
• Number of moles of production and reactant are same D

• Forward A
• Backward B
• Already in equilibrium C
• K_cis never less D