Chemical Effects of Electric Current Class 8 MCQs Questions with Answers
I. Choose the correct option.
Question 1.
Which of the following is a bad conductor of electricity?
(a) Distilled water
(b) Silver nitrate
(c) Sulphuric acid
(d) Copper sulphate
Answer
Answer: (a) Distilled water
Question 2.
Which of the following does not conduct electricity?
(a) Sugar solution
(b) Vinegar solution
(c) Lemon juice solution
(d) Caustic soda solution
Answer
Answer: (a) Sugar solution
Question 3.
An electric current can produce
(a) heating effect
(b) chemical effect
(c) magnetic effect
(d) all of these
Answer
Answer: (d) all of these
Question 4.
Pure or distilled water is a
(a) poor conductor
(b) good conductor
(c) both (a) and (b)
(d) none of these
Answer
Answer: (a) poor conductor
Question 5.
Which of the following is a good conductor?
(a) Brick
(b) Steel
(c) Plastic
(d) Cotton
Answer
Answer: (b) Steel
Question 6.
Polythene is
(a) a conductor
(b) an insulator
(c) both (a) and (b)
(d) none of these
Answer
Answer: (b) an insulator
Question 7.
Electroplating is based on
(a) heating effect of electricity
(b) chemical effect of electricity
(c) physical effect of electricity
(d) magnetic effect of electricity
Answer
Answer: (b) chemical effect of electricity
Question 8.
Copper is
(a) a good conductor
(b) an insulator
(c) both (a) and (b)
(d) none of these
Answer
Answer: (a) a good conductor
Question 9.
Waste from an electroplating factory must be disposed off
(a) in the nearby river
(b) in the nearby pond
(c) in the nearby cornfield
(d) according to the disposal guidelines of Waste Management Bodies
Answer
Answer: (d) according to the disposal guidelines of Waste Management Bodies
Question 10.
An electrolyte is
(a) a metal
(b) a liquid that conducts current
(c) a non-metal
(d) none of these
Answer
Answer: (b) a liquid that conducts current
Question 11.
Flow of electron is called
(a) electrolyte
(b) electroplating
(c) electrodes
(d) electric current
Answer
Answer: (d) electric current
Question 12.
Which is not a non-electrolyte?
(a) Ethyl alcohol
(b) Sodium chloride
(c) Urea
(d) Sodium solution
Answer
Answer: (b) Sodium chloride
Question 13.
An electric lamp glows due to
(a) heating effect
(b) magnetic effect
(c) chemical effect
(d) physical effect
Answer
Answer: (a) heating effect
Question 14.
Electroplating prevents
(a) corrosion
(b) passing of current
(c) dissociation
(d) shining
Answer
Answer: (a) corrosion
Question 15.
Which of the following is not used for electroplating metal articles?
(a) Nickel
(b) Silver
(c) Chromium
(d) Sodium
Answer
Answer: (d) Sodium
Question 16.
Iron objects can be protected by electroplating them with
(a) chromium
(b) nickel
(c) zinc
(d) all of these
Answer
Answer: (d) all of these
II. Fill in the Blanks
Question 1.
Substances that conduct electricity are called ………………
Answer
Answer: Conductors
Question 2.
Substances that do not conduct electricity are called ………………
Answer
Answer: insulator
Question 3.
A cation has ……………… charge.
Answer
Answer: positive
Question 4.
Some liquids are conductors of electricity and some are ……………… conductors of electricity.
Answer
Answer: good, poor
Question 5.
Distilled water is an ………………
Answer
Answer: insulator
Question 6.
Distilled water when mixed with salts becomes a ……………… conductor of electricity.
Answer
Answer: good
Question 7.
Light emitting diodes (LED) glow even when a ……………… electric current flows through it.
Answer
Answer: weak
Question 8.
The passage of an electric current through a conducting solution causes ………………
Answer
Answer: chemical reaction
Question 9.
Change in colour is an example of the ……………… effect of current.
Answer
Answer: chemical
Question 10.
There are ……………… wires attached to an LED.
Answer
Answer: two
Question 11.
In an LED, the longer lead is attached to the ……………… terminal of the battery and the shorter lead to the terminal.
Answer
Answer: positive, negative
Question 12.
Chromium has a ……………… appearance.
Answer
Answer: shiny
Question 13.
Distilled water is made by removing all ………………
Answer
Answer: impurities
Question 14.
Iron tends to ……………… and ………………
Answer
Answer: corrode, rust
Question 15.
A coating of ……………… is deposited on iron to protect it from corrosion and formation of rust.
Answer
Answer: zinc
Question 16.
An electric lamp glows due to ……………… effect of electric current.
Answer
Answer: heating
Question 17.
Electrodes are ………………
Answer
Answer: conductors
Question 18.
The deflection in ……………… shows that current is passing.
Answer
Answer: magnetic compass
Question 19.
……………… does not corrode easily.
Answer
Answer: Chromium
Question 20.
An electrolyte is a ………………
Answer
Answer: liquid
III. True or False
Question 1.
Rubber is a good conductor of electricity.
Answer
Answer: False
Question 2.
Plastics are poor conductor of electricity.
Answer
Answer: True
Question 3.
All liquids conduct electricity.
Answer
Answer: False
Question 4.
Distilled water is free of salt.
Answer
Answer: True
Question 5.
Pure water conducts electricity.
Answer
Answer: False
Question 6.
Most liquids that conducts electricity are solutions of acids, bases and salts.
Answer
Answer: True
Question 7.
Electroplating is based on magnetic effect of electricity.
Answer
Answer: False
Question 8.
Small amount of some mineral salts are naturally present in water.
Answer
Answer: True
Question 9.
Chromium is carcinogenic.
Answer
Answer: True
Question 10.
An electric bulb glows due to chemical effect of electricity.
Answer
Answer: False
Question 11.
Distilled water when mixed with salt conducts electricity.
Answer
Answer: True
Question 12.
LED is an electric bulb which is used in a tester.
Answer
Answer: True
Question 13.
Deflection in compass needle is due to magnetic effect of current.
Answer
Answer: True
Question 14.
When electric current is passed through the copper sulphate solution, copper and sulphate ions are dissociated.
Answer
Answer: True
Question 15.
In an LED bulb, the shorter lead is connected to the positive terminal of the battery.
Answer
Answer: False
Question 16.
Electric current produces a magnetic effect.
Answer
Answer: True
Question 17.
Some liquids are good conductors of electricity and some are poor conductors of electricity.
Answer
Answer: True
Question 18.
Chromium has a shiny appearance.
Answer
Answer: True
Question 19.
Jewellery makers electroplate silver and gold on expensive metals.
Answer
Answer: False
Question 20.
Electroplating wastes are useful to human health and environment.
Answer
Answer: False
IV. Match the following
| Column I | Column II |
| 1. Closed path | (a) Good conductor |
| 2. LED | (b) Deflection of compass |
| 3. Carbon rod | (c) Positively charged ion |
| 4. Galvanisation | (d) Poor conductor of electricity |
| 5. Distilled water | (e) Coating with zinc |
| 6. Salt solution | (f) Electrodes |
| 7. Cation | (g) Light emitting diodes |
| 8. Magnetic effect of current | (h) Electric circuit |
| 9. Chromium | (i) Negatively charged ion |
| 10. Anion | (j) Electroplating |
Answer
Answer:
| Column I | Column II |
| 1. Closed path | (h) Electric circuit |
| 2. LED | (g) Light emitting diodes |
| 3. Carbon rod | (f) Electrodes |
| 4. Galvanisation | (e) Coating with zinc |
| 5. Distilled water | (d) Poor conductor of electricity |
| 6. Salt solution | (a) Good conductor |
| 7. Cation | (c) Positively charged ion |
| 8. Magnetic effect of current | (b) Deflection of compass |
| 9. Chromium | (j) Electroplating |
| 10. Anion | (i) Negatively charged ion |
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