Chemical Effects of Electric Current

Q1. Fill in the blanks.

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

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

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

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

Q2. State True (T) or False (F).

                         i.        A piece of fresh potato does not conduct electricity. F

                        ii.        LED glows even when a low electric current passes through it. T

                       iii.        The passage of an electric current through a conducting solution causes chemical effect. T

                       iv.        Materials such as rubber plastic and wood conduct electricity. F

Q3. Which metal is electroplated on bathroom fittings?

Ans. Chromium is usually electroplated on bathroom fittings.

Q4. Name any one metal which is purified by using the chemical effect of current (or electrolysis).

Ans. Copper

Q5. Do liquids also conduct electricity?

Ans. No, some liquids are good conductors of electricity and some are poor conductors.

Q6. Give one example of the chemical effect of electric current.

Ans. Bubbles of gases are formed when an electric current is passed through acidified water.

 
Q7. How is water decomposed into hydrogen and oxygen?

Ans. Water is decomposed into hydrogen and oxygen by passing electric current through it.

Q8. Name some liquids which conduct electricity.

Ans. Liquids such as vinegar, lemon juice, tap water, rain water and sea water conduct electricity.        

Q9. Name some liquids which do not conduct electricity.

Ans. Liquids such as water, milk, vegetable oil and honey do not conduct electricity.

Q10. State whether vinegar and lemon juice will conduct electricity or not.

Ans. Though vinegar and lemon juice conduct electricity but they are weak conductors of electricity.

Q11. What is electroplating?

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

Q12. What happens to a compass needle kept nearby when current flows in a wire?

Ans. Even if the current is small, the deflection of the magnetic needle can be seen.

Q13. Name a device which glows even when a weak electric current passes through it.

Ans. LED (Light Emitting Diodes) glows even when a weak electric current flows through it.

Q14. Which is the polluting waste generated by electroplating factories?

Ans. The conducting solution used in the electroplating process is the polluting waste generated by electroplating factories.

Q15. What is the advantage of using LED in testing the electrical conductivity of liquids?

Ans. The advantage of using LED in testing the electrical conductivity of liquids is that it glows even when a weak electric current flows through it.

Q16. Does pure water conduct electricity? If not, what can we do to make it conducting?

Ans. Pure water is free of salts and is a poor conductor. We can add some common salt in pure water to make it conducting.

Q17. Name two metals which are usually electroplated on cheaper metals for making jewelry (or ornaments).

Ans. Silver and gold are usually electroplated on cheaper metals for making jewelry (or ornaments).

Q18. Which effect of electric current is utilized for detecting the flow of current through a solution when a compass is used?

Ans. Magnetic effect of electric current is utilized for detecting the flow of current through a solution when a compass is used.