ECAT Pre Engineering Chemistry Chapter 8 MCQ Test With Answer

When H₂and I₂are mixed and equilibrium is attained, then

• Amount of HI formed is equal to the amount of H₂dissociated A
• HI dissociation stops B
• The reaction stops completely 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

When a weak acid is dissolved in water or a weak base dissolved in water, then in both cases the conjugate acid base pair is produced. The ionization constants K_aand K_bof a pair are related with each other as

• K_a= K_b A
• K_a. K_b= K_w B
• K_a. K_w= K_b C
• K_b. K_w= K_a D

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

• 0.5 A
• 4.0 B
• 2.5 C
• 0.25 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

Which of the following in an example of reversible reaction

• 
  A
• 
  B
• 
  C
• 
  D

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

K_avalue of HF acid is 6.7 x 10^-15the acid is a

• Weak acid A
• Moderately strong acid B
• Strong acid C
• Very weak acid D

The ionic product of H⁺ions and OH^-in water is called ionization constant of water Kw. The value of Kw at 25°C is

• 0.11 x 10^-14 A
• 0.30 x 10^-14 B
• 1.0 x 10^-14 C
• 3 x 10^-14 D

2SO₂ + O₂ ⇌ 2SO₂ H= 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 V₂O₅ catalyst increase the equilibrium yield of Sulphur trioxide.
  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

• 8 A
• 4 B
• 9 C
• 3 D

Which statement about the following equilibrium in correct?

2SO_{2 (g)}+ O_2(g)---------------2sO_3(g)H= - 188.3 KJ mol-1

• T value of K_{p falls witha rise in temperate.} A
• The value of K_{p falls withincreasing pressure}
  B
• Adding V_2O5catalyst increase the equilibrium yield of sulfur trioxide
  C
• The value of K_{p is equal to}K_p D
• 
  
  E

A buffer solution of 0.1 molar HCOOH and 0.1 molar HCCONa has pH = 3.78 To is 0.01 molar HCl is added, then pH of the buffer solution becomes

• 2.78 A
• 4.78 B
• 3.78 C
• 3.70 D

The value of K_pis greater than K_cfor a gaseous reaction when

• Number of molecules of products is greater than the reactants A
• Number of molecules of reactants is greater than those of products B
• Number of molecules of reactants and products equal C
• Catalyst is added D

The relation between Kc and Kp is

• 
  A
• 
  B
• 
  C
• 
  D

• 
  A
• 
  B
• 
  C
• 
  D

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

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

Units of Kw are

• Mole dm^-3 A
• Mole²dm^-3 B
• Mole²dm^-6 C
• Mole²dm^-3 D

The correct relation b/wK_{c and}K_{p is :}

• K_p = K_c[P/N] ^Δn

  A

• K_{c =} K_p(RT) ^Δn

  B

• K_{p =} K_c(RT) ^Δn

  C

• K_{p =} K_c(RT) ^Δn

  D

A solution of NaOH has pH = 13, then concentration of NaOH is

• 10^-13M A
• 10¹³M B
• 10^-1M C
• 10⁺¹M 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

In a lime kiln, to get higher yield of CO₂, the measure that can be taken is

• To main high temperature A
• To pump out CO₂ B
• To remove Cao C
• To add more CaCO₃ D

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

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

• 0.02 A
• 0.2 B
• 50 C
• 25 D

The avtive mass of 64 g of HI in a two litre flask would be

• 2 A
• 1 B
• 5 C
• 0.25 D

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

• Increase in concentration of 1 A
• Decrease in concentration of I₂ B
• Increase in temperature C
• Increase in total pressure D