INTRODUCTION - Chapter 14 - Chemical Effects Of Electric Current - Ncert Solutions class 8 - Science

Share this to Friend on WhatsApp

Question 1:

Fill in the blanks.

(a) Most liquids that conduct electricity are solutions of ________, _______ and ________.

(b) The passage of an electric current through a solution causes _________ effects.

(c) If you pass current through copper sulphate solution, copper gets deposited on the plate connected to the __________ terminal of the battery.

(d) The process of depositing a layer of any desired metal on another material by means of electricity is called _________.

Answer:

(a) Most liquids that conduct electricity are solutions of __acids__, __bases__ and __salts__.

(The solutions of acids, bases or salts are conducting in nature. They allow the current to pass through.)

(b) The passage of an electric current through a solution causes __chemical__ effects.

(When an electric current passes through a solution, the solution decomposes into its positive and negative ions. This process of decomposition of the solution is a chemical effect.)

(c) If you pass current through copper sulphate solution, copper gets deposited on the plate connected to the __negative__ terminal of the battery.

(When an electric current passes through a copper sulphate solution, the solution decomposes into positively charged copper ions and negatively charged sulphate ions. These positively charged copper ions get attracted towards the plate which is connected to the negative terminal of a battery.)

(d) 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 in the compass needle shows that current is flowing through the wounded wire and hence, through the circuit. The circuit is complete since free ends of the tester are dipped in a solution. The solution is certainly a conducting solution. This is the reason why the compass needle shows a deflection.

Question 3:

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

Answer:

Liquids like lemon juice, salt water and mercury allow electricity to pass through them. Hence, these liquids can be used as in the beaker to show the given effect.