ECAT Pre Engineering Chemistry Chapter 8 MCQ Test With Answer

• 0.02 A
• 0.2 B
• 50 C
• 25 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

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

At certain temperature, 50% of HI is dissociated into H₂and I₂the equilibrium constant is

• 1.0 A
• 3.0 B
• 0.5 C
• 0.25 D

K_bfor NH₄OH is 1.81 x 10^-5, then K_avalue of its conjugate base is

• 1.81 x 10⁺⁵ A
• 1.81 x 10^-9 B
• 5.5 x 10^-9 C
• 5.5 x 10^-10 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

A chemical reaction is in equilibrium when

• Formation of product is minimum A
• Reactants are completely transformed into products B
• Rates of forward and backward reactions are equal C
• Equal amounts of reactants and products are present 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

• 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 an exothermic reaction, a 10° rise in temperature will

• Decrease the value of equilibrium constant A
• Double the value of K_c B
• Not produce any change in K_c C
• Produce some increase in K_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

• 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

The ionization constant of an acid is expressed in term of the following constant

• Kw A
• Kn B
• Ka C
• Kb 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

K_bvalue of NH₄OH is 1.81 x 10^-5and its conjugate acid has K_a= 5.7 x 10^-10pKb of the base is 4.74, pKa of its conjugate acid is

• -4.74 A
• 4.74 B
• 10 C
• 9.26 D

• Shift reaction toward forward direction A
• Shift reaction backward B
• Lower the value of K_c C
• No change in reaction 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

A large value of K_cmeans that at equilibrium :

• Less reactant and more products. A
• Reactants and product in same amounts. B
• More reactants and less products. C
• None of above. D

The solubility product of AgCl is 2.0 x 10^-10mol²dm^-6The maximum concentration of Ag⁺ions in the solution is

• 2.0 x 10^-10mol dm^-3 A
• 1.41 x 10^-5mol dm^-3 B
• 1.0 x 10^-10mol dm^-3 C
• 4.0 x 10^-20mol dm^-3 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

According to Le-Chatelier's principal, adding heat to a solid and liquid in equilibrium will cause the

• Amount of solid to decrease A
• Amount of liquid to decrease B
• Temperature to rise C
• Temperature to fall D

• 8 A
• 4 B
• 9 C
• 3 D

• 0.073 A
• 0.147 B
• 0.05 C
• 0.026 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

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

• Ag⁺ and NO_3- only

  A

• Ag⁺ and Ba² and NO^-3

  B

• Ba² and NO^-3

  C

• Ba² and NO^-3 and Cl-

  D

The ph of 10-3 mole dm-3 of an aqueous solution of H₂SO₄ is :

• 3.0

  A

• 2.7

  B
• 2.0 C

• 1.5

  D

pH of 1 molar NaOH is

• 7 A
• zero B
• 14 C
• 10 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

If pH of buffer of 1 mole dm^-3of HCOOH + 0.1 mole dm^-3HCOONa having pKa = 3.78 is

• 1.78 A
• 2.78 B
• 3.78 C
• 4.78 D