8th Class Science Chemical Effects of Electric Current Question Bank

done Chemical Effects of Electric Current Total Questions - 20

• question_answer1)
  In the given figure, electrolyte, anode and cathode respectively are
  A)
   A, B and C                 done clear
  B)
   B, A and C     done clear
  C)
   B, C and A                 done clear
  D)
   A, C and B done clear
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• question_answer2)
  In which of the following will the bulb glow?
  A)
    done clear
  B)
    done clear
  C)
            done clear
  D)
              done clear
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• question_answer3)
  In which one of the following situations does a conventional electric current flow due north?
  A)
   Protons in a beam are moving due south. done clear
  B)
   A water molecule is moving due north. done clear
  C)
   Electrons in a beam are moving due south. done clear
  D)
   None of these done clear
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• question_answer4)
  The diagram shows a beaker containing a solution of zinc sulphate and two carbon electrodes. A battery is placed next to it. In order that the electrode P be plated with zinc,
  A)
   P must be connected to S and Q to R done clear
  B)
   P must be connected to Q and S to R done clear
  C)
   P must be connected to R and Q to S done clear
  D)
   P and Q must be connected to R. done clear
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• question_answer5)
  In the experiment, if A is plated with copper, the anode would be
  A)
   A                                 done clear
  B)
   B                     done clear
  C)
   C                                done clear
  D)
   Data insufficient done clear
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• question_answer6)
  When electricity is passed through calcium nitrate solution in water, what is likely to be formed at the cathode and why?
  A)
   Hydrogen because it is a very reactive than calcium done clear
  B)
   Calcium because it is a very reactive than hydrogen done clear
  C)
   Hydrogen because it is less reactive than calcium done clear
  D)
   Calcium because it is less reactive than hydrogen. done clear
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• question_answer7)
  An electric current is passed through a conducting solution. Following are the some observations:

  (i) Deposits of metal may be seen on electrodes

  (ii) Solution may get heated

  (iii) Bubbles of gas may be formed on the electrodes

  A)
   Only (ii) is true. done clear
  B)
   Only (i) and (ii) are true. done clear
  C)
   Only (i) and (iii) are true. done clear
  D)
   All (i), (ii) and (iii) are true. done clear
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• question_answer8)
  In the given figure, the filter paper contains starch soaked in potassium iodide solution is connected to the battery as shown. When we write on the wet paper, it has a blue black colour.

  (i)  Iodine is formed at the anode.

  (ii) Iodine turns blue black in the presence of starch.

  A)
   Only (i) is correct. done clear
  B)
   Only (ii) is correct. done clear
  C)
   Both (i) and (ii) are correct. done clear
  D)
   Neither (i) nor (ii) is correct. done clear
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• question_answer9)
  Which of the following statements is incorrect?
  A)
   Anode is an electrode connected to the positive terminal of the battery. done clear
  B)
   Pure water is poor conductor of electricity. done clear
  C)
   Electrolysis is used in the refining of impure metals. done clear
  D)
   Ions can have only a positive charge. done clear
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• question_answer10)
  Which of the following is correct?
  A)
   Water can be used for extinguishing fires caused due to electrical faults. done clear
  B)
   Carbon is a non-metal so it cannot be used in electrolytic cell. done clear
  C)
   A liquid conducts electricity because of the presence of ions. done clear
  D)
   Pure water forms ions to conduct electricity. done clear
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• question_answer11)
  Which of the following cells use(s) electric current to produce a chemical reaction?
  A)
   Dry cell done clear
  B)
   Solar cell done clear
  C)
   Electrolytic cell done clear
  D)
   Both dry cell and electrolytic cell done clear
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• question_answer12)
  Electrolysis of a solution of sodium chloride produces
  A)
   Hydrogen gas at anode and chlorine at cathode done clear
  B)
   Hydrogen gas at cathode, chlorine at anode and sodium hydroxide done clear
  C)
   Hydrogen gas at anode and sodium hydroxide at cathode done clear
  D)
   Chlorine gas at anode and sodium hydroxide at cathode. done clear
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• question_answer13)
  Adding common salt to distilled water makes it
  A)
   Good conductor done clear
  B)
   Insulator done clear
  C)
   Can't say done clear
  D)
   None of these done clear
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• question_answer14)
  Why is the switch for any electrical appliance in ac circuit always connected to the live wire?
  A)
   No current flows in the neutral wire. done clear
  B)
   There will be a short circuit if the switch is in the Earth lead. done clear
  C)
   The device can be switched off easily if the switch is in the neutral lead. done clear
  D)
   The device can be isolated (mode safe) if the switch is in the live lead. done clear
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• question_answer15)
  To protect iron from corrosion and rust, it is coated with
  A)
   Tin                              done clear
  B)
   Copper           done clear
  C)
   Mercury                      done clear
  D)
   Zinc. done clear
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• question_answer16)
  There are two different solutions in set up P and Q as shown in figure. The bulb in the set up P glows more brightly as compared to that of the set up Q. What are the possible causes for this?

  (i) The connections of the circuit Q may be loose.

  (ii) The liquid in Q may have small conductivity.

  (iii) Liquid in P is equivalent to a battery while liquid in Q is equivalent to a cell of the battery of liquid P.

  A)
   Only (i) and (ii)           done clear
  B)
   Only (ii) and (iii) done clear
  C)
          Only (i)                       done clear
  D)
   Only (ii) done clear
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• question_answer17)

  Direction: Four substances were tested for their electrical conductivity. The results are shown in the table. Study the table and answer the following questions.
  Substance	Bulb	Substance at Cathode	Substance at Anode
  P	Lights up	Aluminium	Oxygen
  Q	Lights up	Nothing	Nothing
  R	Does not light up	Nothing	Nothing
  S	Lights up	Hydrogen	Carbon dioxide

  In substance Q, bulb lights up but no substance is found either at cathode or at anode, why?
  A)
   Because Q is non-electrolyte. done clear
  B)
   Because Q is an element which remains unchanged when it conducts electricity. done clear
  C)
   Because Q is an electrolyte that conducts electricity when it is in the molten state. done clear
  D)
   Because Q is a poor conductor of electricity. done clear
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• question_answer18)

  Direction: Four substances were tested for their electrical conductivity. The results are shown in the table. Study the table and answer the following questions.
  Substance	Bulb	Substance at Cathode	Substance at Anode
  P	Lights up	Aluminium	Oxygen
  Q	Lights up	Nothing	Nothing
  R	Does not light up	Nothing	Nothing
  S	Lights up	Hydrogen	Carbon dioxide

  Which solutions could be alumina and magnesium nitrate respectively?
  A)
   P and Q done clear
  B)
   R and Q done clear
  C)
   P and S done clear
  D)
   P is the alumina but no one is magnesium nitrate. done clear
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• question_answer19)
  The bumpers and door handles of motor cars, taps etc. are coated with silvery layer of chromium because

  (i)  It does not easily get corroded.

  (ii) It forms a hard layer which does not easily get scratched.

  (iii) It tarnishes quickly.

  (iv) It is cheap.

  Which of the following options is correctly identifies true (T) or false (F)?
  A)

  (i)	(ii)	(iii)	(iv)
  F	F	T	T

    done clear
  B)

  (i)	(ii)	(iii)	(iv)
  T	T	F	F

    done clear
  C)

  (i)	(ii)	(iii)	(iv)
  F	T	F	T

    done clear
  D)

  (i)	(ii)	(iii)	(iv)
  T	T	F	T

    done clear
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• question_answer20)
  The diagram shows a plotting compass placed above a copper wire when there is no current flowing in the wire. What happens to the compass needle when a large direct current flows from point A to point B?
  A)
   The compass needle points towards the right. done clear
  B)
   The compass needle points towards the left. done clear
  C)
   The compass needle points towards upward. done clear
  D)
   The compass needle points toward downward. done clear
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