Class 8 Chemical Effects of current

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Multiple Choice Questions (MCQs)

  1. Which of the following is an insulator?

(a) Human body

(b) Graphite

(c) Pure water

(d) Copper

  1. In electroplating, the object to be electroplated is made:

(a) anode

(b) cathode

(c) none

(d) both

  1. The extraction of metals from their ores by electrolysis is called:

(a) electroplating

(b) electrometallurgy

(c) electrorefining

(d) none

  1. The refining or purification of metals by passing electric current is called:

(a) electroplating

(b) electrolysis

(c) electrorefining

(d) none

  1. Carbon rods, used as electrodes are made up of:

(a) graphite

(b) wood

(b) iron

(d) diamond

  1. Which of these are the applications of electrolysis?

(a) Metal Extraction

(b) Electroplating

(c) Electrorefining

(d) All these

  1. In an electrolytic cell, the electrode which is connected to the positive terminal of the battery is called:

(a) cation

(b) anion

(c) cathode

(d) anode

  1. Which of these is plated on the iron to prevent it from chemically reacting with food?

(a) Gold

(b) Silver

(c) Chromium

(d) Tin

  1. Out of the following, which metal is used to electroplate iron to make it shining and rust resistant?

(a) Chromium

(b) Gold

(c) Zinc

(d) Copper

Fill in the blanks:

  1. Electroplating is based on the —chemical—-effect of electric current.
  2. Wood is a—bad— conductor of electricity.
  3. Pencil lead is a.
  4. The flow of electrons is called—current—.
  5. Tap water is a—good conductor of electricity.
  6. Tap water conducts electricity because it has dissolved in it.
  7. The process used to purify a metal is called —-electroplating.

State whether ‘True’ (T) or ‘False’ (F):

  1. Chromium corrodes easily. F
  2. The sugar solution is an electrolyte. F
  3. Cations are negatively charged particles. T
  4. Electrolytes produce ions when dissolved in water. T
  5. A cycle rim is made of iron that is electroplated with chromium. T
  6. Touching an electrical appliance with wet hands can be very dangerous. T


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