ECAT Pre Engineering Chemistry Chapter 8 MCQ Test With Answer

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

• 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

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

• Decrease in temperature favour more dissolution of the salt A
• Increase in temperature favour more dissolution of the salt B
• Lowering pressure favour more dissolution of the salt C
• Increasing pressure favour more dissolution of the salt D

In 1000 molecules of 0.001 M acetic acid the number of H⁺ions is 12.6, then its percentage of ionization is

• 1.33% A
• 1.26% B
• 12.6 C
• 1% D

A gas bulb is filled with NO₂gas and immersed in an ice bath at 0°C which becomes colourless after sometimes. This colourless gas will be

• NO₂ A
• N₂O B
• N₂O₄ C
• N₂O₅ D

• Initial concentration of acetic acid A
• Initial concentration of ethyl acetate B
• Equilibrium concentration of acetic acid C
• Equilibrium concentration of ethyl acetate 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

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

• 0.60 A
• 1.67 B
• 0.66 C
• 2.6 D

A solution has pH = 0, its H⁺ion concentration is

• 1 x 10^-14 A
• 1 x 10¹⁴ B
• 1 x 10¹ C
• 1 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

Which of the following factors will favour the reverse reaction in a chemical equilibrium?

• Increase in concentration of one of the reactants A
• Increase in concentration of one of the products B
• Removal of one of the products regularly C
• None of these D

N₂ +3H₂⇌ 2NH_{3 + Heat for above equation, themaximum product will be obtained at :}

• Low temperature at high pressure. A
• High temperature and low pressure. B
• High temperature and high pressure. C
• Low temperature at low pressure. D

Almost forward reaction is complete when value of k_{c :}

• Neither larger nor very small. A
• Very small. B
• Very large. C
• Negligible. 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

• 450°C A
• 250°C B
• 850°C C
• 1000°C D

• Equal volumes of N₂and H₂are reacting A
• Equal masses of N₂and H₂are reacting B
• The reaction has stopped C
• The same amount of ammonia is formed as is decomposed into N₂and H₂ D

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

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

N₂ + 3H₂ ⇌2NH₃

The unit of K_c for tis reaction will be:

• mol² dm^-6

  A

• mol^-2 dm⁺⁶

  B

• mol dm^-3

  C

• mol^-1 dm⁺³

  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

A reaction is reversible because :

• Products are stable. A
• Reactants are reactive. B
• Products are reactive. C
• Reactants re stable. 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

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

A solution having pH = 4 its OH^-ion concentration in mole dm^-3is

• 1.0 x 10^-4 A
• 1.0 x 10^-10 B
• 1.0 x 10^-14 C
• 1 x 10⁰ D

pH of 0.1 molar HCl solution is

• 1 A
• zero B
• 13 C
• 14 D

Hydrogen gas and iodine vapours combine to form Hl at 425°C, the same composition of mixture is present if we start with decomposition of Hl. It suggests

• A static equilibrium A
• Law of mass action B
• A dynamic equlibrium C
• Irreversible reaction 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

Addition of solid NaHCO₃in water causes ionization of NaCHO₃its K_a= 4.7 x 10^-1. Then this solution has character

• Acidic A
• Very weakly basic B
• Alkaline C
• Neutral D

Which one of the following is a buffer

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