ECAT Pre Engineering Chemistry Chapter 8 MCQ Test With Answer

Base buffer solution can be prepared by mixing

• Weak acid and its salt A
• Strong acid and its salt with weak base B
• Weak base and its salt with strong acid C
• Strong base and its salt with weak acid 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

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

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

Ammonium carbonate when heated to 200°C gives a mixture of NH₃and CO₂vapour with a density of 13.0. What is the degree of dissociation of ammonia carbonate?

• 3/2 A
• 1/2 B
• 2 C
• 1 D

• HF is stable and does not decompose even at 2000°C A
• HF is stable and slowly decomposes at 2000°C B
• HF is strong acid C
• HF produces equal moles of hydrogen and fluorine D

• 0.02 A
• 0.2 B
• 50 C
• 25 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

For which system does the equilibrium constant, kc has units of (concentration) ?

• N₂+3H_2-------2NH₃

  A

• H₂+L₂---------2HL

  B

• 2NO₂----------N₂O₄

  C

• 2HF--------H2+F₂

  D

• High temperature and low pressure A
• Low temperature and low pressure B
• Low temperature and high pressure C
• High temperature and high pressure 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

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

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

What happens when reaction is at equilibrium and more reactant is added :

• Forward reaction rate is increased. A
• Forward reaction rate is decreased. B
• Backward reaction rate is increased. C
• Equilibrium remains unchanged. 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

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

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

Acetic acid is 1.33% ionized, In 1000 molecules of 0.1 M acetic acid the number of H⁺ions is

• 1.33 A
• 13.3 B
• 1.33 C
• 1 D

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

• [A] = [B] A
• [A] < [B] B
• [B] = [C] C
• [A] > [B] D

A reaction is reversible because :

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

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

• At equilibrium there is no further change in the concentration of Hl A
• At equilibrium concentration of l₂remains constant B
• At equilibrium concentration of H₂remains unaltered C
• At equilibrium the rate of formation of Hl is equal to the rate of decomposition of Hl D

An aqueous solution is neutral when its

• pH = 14 A
• pH = zero B
• pH = 7 C
• Kw = 10^-7 D

On passing HCI gas through a saturated solution of commercial sodium chloride, pure crystals of NaCI are precipitated due to

• Increase in pH of the solution A
• Decrease in pH of the solution B
• Common ion effect C
• Increase in ionization of NaCl 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

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

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

Product of concentration of ions raised to the power equal to the co-efficient of ions in balanced equation for saturated solution of a salt is called

• Ionic product A
• Equilibrium constant K_c B
• K_w C
• Solubility product (K_sp) D

• 32 A
• 64 B
• 16 C
• 4 D