ECAT Pre Engineering Chemistry Chapter 8 MCQ Test With Answer

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

Le-chatlier's principle is applied on the reversible reaction in order to

• Determine the rate of reaction A
• Predict the direction of reaction B
• Determine the extent of reaction C
• Find best conditions for favorable shifting the position of equilibrium 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

N₂3H₂⇌ 2NH₃

_{Which of the following change will favorthe formation of more}NH₃at equilibrium in above reaction :

• By adding NH_3. A
• By removingH_2. B
• By decreasing pressure. C
• By increasing pressure. D

Whenever a week base is dissolved in water, it give its conjugate acid. similarly a weak acid in water produces its conjugate base. This conjugate acid-base pair concept is stated by

• Law of mass action A
• Le-charlier's principle B
• Common ion effect C
• Lowery Bronsted concept 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

The best buffer is prepared when molar concentrations of the salt and acid are equal, then its pH and pKa value are related

• pH = pKa A
• pH < pKa B
• pH > pKa C
• pH x pKa = 14 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

Which of the following is a characteristic of a reversible reaction?

• It never proceeds to completion A
• It can be influenced by a catalyst B
• It proceeds only in the forward direction C
• Number of moles of reactants and products are equal 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 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

• Low pressure A
• High pressure B
• High temperature C
• High concentration of SO₂ 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

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

Reactions that proceed on both sides and never go to completion are called

• Irreversible reactions A
• Reversible reactions B
• Opposing reactions C
• Spontaneous reactions D

• 0.60 A
• 1.67 B
• 0.66 C
• 2.6 D

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

1 mol of N₂O₄ was decomposed according to given equation in 1dm₃ container. At equilibrium x mole of N₂O₄ have dissociated. What is the value of K_C:

• 2x/(1-x)²

  A

• 4x²/(1-x)

  B

• 4x/(1-x)

  C

• 2x/(1-x)

  D

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

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

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

• 2 A
• 1 B
• 5 C
• 0.25 D

• 
  A
• 
  B
• 
  C
• 
  D

• 8 A
• 4 B
• 9 C
• 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

• 0.073 A
• 0.147 B
• 0.05 C
• 0.026 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

• Total pressure A
• Amount of A₂and B₂ B
• Temperature C
• Catalyst D

pH and pKa of the buffer are related by Henderson equation which is

• 
  A
• 
  B
• 
  C
• 
  D