NCERT Class VIII Science Solutions: Chapter 14-Chemical Effects of Electric Current Part 5

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Question 19:

In the circuit given as Fig. Boojho observed that copper is deposited on the electrode connected to the negative terminal of the battery. Paheli tried to repeat the same experiment. But she could find only one copper plate. Therefore she took a carbon rod as negative electrode. Will copper be still deposited on the carbon rod? Explain your answer.

As showing in fig is a Cppper plate in connected battery

Cppper Plate in Connected Battery

As showing in fig is a Cppper plate in connected battery

Answer:

Yes, copper from the copper sulphate solution will be deposited on the carbon rod. Copper from the copper plate will be dissolved into the copper sulphate solution for electroplating.

Question 20:

Observe the circuit given in Fig.

As showing in fig is a process of purification.

Process of Purification.

As showing in fig is a process of purification.

Boojho set up this circuit for purification of copper. What will be the nature of -

  1. Plate A

  2. Plate B

  3. The solution.

Explain the process of purification.

Answer:

  1. Plate A – Pure copper

  2. Plate B – Impure copper

  3. The solution – Copper sulphate

Copper from impure copper plate is transferred to the pure copper plate by the process of electroplating.

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