ECAT Pre Engineering Chemistry Chapter 10 MCQ Test With Answer

During redox reaction an oxidizing agent

• Gains electrons A
• Is oxidized B
• Loses electrons C
• Hydrolysed D

Most metals are conductors of electricity because of the :

• Light weight. A
• Immobility of the electrons. B
• Lustrous surfaces C
• Relatively free movement of their electrons D

A cell in which spontaneous redox reaction generates an electric current is called

• Electrolytic cell A
• Electrochemical cell B
• Voltaic or Galvanic cell C
• Biological cell D

While balancing an equation by ion electron method, the number of oxygen atoms are balanced by

• OH^- A
• H₂O B
• O₂ C
• H⁺ D

Fe can displace Cu form CuSO4solution because

• Fe is ferromagnetic A
• Fe is below Cu in electrochemical series B
• Fe is above Cu in electrochemical series C
• Fe exists in divalent oxidation state D

In passage of electricity through aqueous solution of AgNO₃silver dissolves at anode to form Ag⁺, the electrodes are

• Silver metal A
• Pt metal B
• Graphite C
• Copper metal D

The best electrode used in salt bridge is KCl. Which other electrolyte an also be used for the purpose :

• NaCl A

• NH₄NO₃

  B

• KNO₃

  C

• NaNO₃

  D

Which of the following cannot conduct electricity :

• NaCl fused. A
• NaCl(aq)
  B
• NaCl(Solid)
  C
• Both (b) and (c) D

Which of the following statement is incorrect about SHE(Standard hydrogen electrode):

• Reduction potential of Cu⁺² is smaller than H⁺ions whenit is coupled with copper electrode. A
• gas is passed in it at 1 atm pressure. B
• Its oxidation potential and reduction potential is zero. C
• It is made of platinum wire dipped in HCl solution D

Electrolytes in the form of solution or in the fused state have the ability to conduct :

• Light. A
• Electricity. B
• Ions. C
• Electrons. D

When during electrolysis of a solution of AgNO₃, 9650 coulombs of charge pass through the electroplating bath, the mass of silver deposited on the cathode will be

• 1.08 g A
• 10.8 g B
• 21.6 g C
• 108 g D

96500 C of electricity liberates from CuSO₄solution

• 63.5 g of Cu A
• 31.75 g of Cu B
• 96500 g of Cu C
• 100 g of Cu D

In the electrolysis of aqueous solution of sodium nitrate, the ions which are reduced at the cathode are

• H₃O⁺ A
• Na⁺ B
• OH^- C
• NO^3- D

During electrolysis, the reaction that takes place at cathode is :

• Reduction A
• Both (a) and (c) B
• Oxidation C
• No reaction occurs D

In the electrolysis of fused bauxite (Al₂O₃2H₂O) with fused Cryolite (Na₃AlF₆) using carbon rods as anode. The product obtained at cathode is

• Na metal A
• F₂gas B
• Al metal C
• O₂gas D

The two half cells of a galvanic cell are connected by

• Ammeter A
• Salt bridge B
• Hydrogen electrode C
• Copper electrode D

In a compound an atom has negative oxidation state because

• Atom is negatively charged A
• Atom acts as cathode B
• Atom is more electronegative C
• Atom has lowest ionization energy D

If the salt bridge is not used between two half cells, then the voltage

• Decrease rapidly A
• Decrease slowly B
• Does not change C
• Drops to zero D

The function of salt bridge in the galvanic or voltaic cell is to

• Carry out oxidation at anode A
• To carry out reduction at cathode B
• Carry out electrolysis C
• To prevent the net charge accumulation in either of the half cells D

K,Ca and Li metals may be arranged in decreasing order of their reduction potential as :

• Li, k, Ca A
• Ca, K, Li B
• Li, Ca, K C
• K, Ca, Li D

The amount of electricity that can deposit 108 g of silver from silver nitrate solution is

• 1 ampere A
• 1 coulomb B
• 1 faraday C
• 2 ampere D

The value of SHE is cathode and anode is always taken to be

• One A
• Zero B
• Different C
• Same D

If a salt bridge is removed between the two half cells, the voltage

• Drops to zero A
• Does not change B
• Increases gradually C
• Increases rapidly D

The oxidation number of free element is always taken to be

• 0 A
• 1 B
• 2 C
• -1 D

Matals usually conduct electricity because

• There are mobile electrons in the metallic structure A
• Metals are decomposed by current B
• Metals have high resistance C
• In metals the ions are free to move D

In the reaction K₂Cr₂O₇+ HCl + CrCl₃+ Cl₂+ H₂O the element which is reduced is

• K A
• Cl B
• Cr C
• H D

• Zn A
• H B
• S C
• O D

Cell potential depends upon :

• Concentration of ions A
• Nature of electrolyte B
• Temperature C
• All of above D

Which statement is incorrect for balancing of redox reactions by ion-electron method

• The reaction is splitted into two half reactions A
• H₂O and H⁺ions are added for acidic or neutral reaction to balance O and H atoms B
• To balance H, HCi, is added C
• To balance O and H in the alkaline reaction OH^-added D

The cathodic reaction in the electrolysis of dill H₂SO₄with Pt electrodes

• Reduction A
• Oxidation B
• Both oxidation and reduction C
• neither oxidation or reduction D