NCERT Class VIII Science Solutions: Chapter 14-Chemical Effects of Electric Current Part 1

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Question 1:

Fill in the blanks.

  1. Most liquids that conduct electricity are solutions of _________, __________ and ________.

  2. The passage of an electric current through a solution causes ____________ effects.

  3. If you pass current through copper sulphate solution, copper gets deposited on the plate connected to the ____________ terminal of the battery.

  4. The process of depositing a layer of any desired metal on another material by means of electricity is called ____________.

Answer:

Fill in the blanks.

  1. Most liquids that conduct electricity are solutions of acids, bases and salts.

  2. The passage of an electric current through a solution causes chemical effects.

  3. If you pass current through copper sulphate solution, copper gets deposited on the plate connected to the negative terminal of the battery.

  4. The process of depositing a layer of any desired metal on another material by means of electricity is called electroplating.

Question 2:

When the free ends of a tester are dipped into a solution, the magnetic needle shows deflection. Can you explain the reason?

Answer:

The deflection of magnetic needle indicates electric current is flowing through the wire. It means the liquid or the solution is a good conductor of electricity. When the free ends of a tester are dipped into a solution, electric circuit is completed and an electric current passes through the solution.

Question 3:

Name three liquids, which when tested in the manner shown in Fig.14.9, may cause the magnetic needle to deflect.

As showing in images is a Electrical circuit for liquids test

Electrical Circuit for Liquids Test

As showing in images is a Electrical circuit for liquids test

Answer:

Ground water, vinegar, citric fruit juice. The liquid solutions containing salts (basic or acidic) will conduct electricity.

Question 4:

The bulb does not glow in the setup shown in Fig. List the possible reasons. Explain your answer.

As showing in images is a Electrical circuit

Electrical Circuit

As showing in images is a Electrical circuit

Answer:

There may be the following possible reasons for not to glow:

  • Liquid solution in container is distilled water.

  • Bulb may be fused.

  • The battery has already been exhausted, there are no sufficient charges (electric current) required for the bulb to glow.

  • Any loose connection (air gaps) like electrodes are not properly connected to wire.