ECAT Pre Engineering Chemistry Chapter 8 MCQ Test With Answer

pH of the human blood which is essentially maintained constant due to carbonates, biocarbonates, phosphates etc., is

• 7.00 A
• 7.25 B
• 7.35 C
• 7.47 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

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

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 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

In which of the following cases, the reaction goes farthest to completion

• K = 10³ A
• K = 10^-2 B
• K = 10 C
• K = 10⁰ 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

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

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 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

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

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

• 2 A
• 1 B
• 5 C
• 0.25 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

pKb value of NH₄OH is 4.74. If the concentration of NH₄OH is 1 molar containing 0.1 molar NH₄Cl, then pH of this buffer will be

• 3.74 A
• 10.26 B
• 4.74 C
• 9.26 D

• 8 A
• 4 B
• 9 C
• 3 D

• 0.073 A
• 0.147 B
• 0.05 C
• 0.026 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 rate of which the reaction proceeds is directly proportional to the product of the active masses of the reactants is according to

• Law of mass action A
• Le Chateliers principle B
• Equilibrium law C
• Law of constant proportion 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

A reaction is reversible because :

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

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

For the above reaction the relationship b/w k_c and k_p will be :

• K_p = K_cRT

  A

• Kp = K_c(RT)_-1

  B

• K_p = K_c(RT)_-2

  C

• K_c = K_p

  D

ph of the buffer CH₃COOh + CH₃COONa is 3.76. If the mixture contains 1 molar acetic acid and 0.1 molar sodium acetate, then pKa of this buffer is

• 3.76 A
• 4.76 B
• 5.76 C
• 6.76 D

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

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

The concentration of reactants is increased by x, then equilibrium constant K becomes

• ln K/x A
• K/x B
• K + x C
• K D