MCQ on Chemical Effects of Electric Current Class 8
Choose the correct answer.
Question 1.
Which of the following is a poor conductor of electricity ?
A) copper
B) iron
C) saltwater
D) air
Answer:
D) air
Question 2.
Which of the following is a good conductor of electricity ?
A) copper
B) glass
C) pure water
D) air
Answer:
A) copper
Question 3.
Which of the following is an alternative to get accurate result when testing for the conductivity of electricity by using a tester?
A) tube
B) halogen
C) LED
D) CFL
Answer:
C) LED
Question 4.
Which of the following liquid is a good conductor of electricity?
A) sugar solution
B) coconut oil
C) pure water
D) vinegar
Answer:
D) vinegar
Question 5.
A tester with a magnetic needle compass can show the deflection in
A) sugar solution
B) coconut oil
C) pure water
D) lemon juice
Answer:
D) lemon juice
Question 6.
A tester with a LED can glow in
A) salt solution
B) acids
C) bases
D) above all
Answer:
D) above all
Question 7.
LED means
A) light emitting device
B) light emitting diode
C) light effect diode
D) low emitting diode
Answer:
B) light emitting diode
Question 8.
Which of the following tester can work even in flow of small currents?
A) bulb tester
B) LED tester
C) compass tester
D) B and C
Answer:
D) B and C
Question 9.
The longer lead of LED is always connected to the …….. terminal of the battery.
A) positive
B) negative
C) A or B
D) none of the above
Answer:
A) positive
Question 10.
If the tester of magnetic compass shows deflection in liquids then the liquid is ……….
A) a poor conductor
B) a good conductor
C) insulator
D) A or B
Answer:
B) a good conductor
Question 11.
The tester of magnetic compass does not show deflection in
A) sea water
B) tap water
C) distilled water
D) salt water
Answer:
C) distilled water
Question 12.
………., when dissolved in distilled water, makes it a good conductor.
A) vinegar
B) caustic soda
C) common salt
D) above all
Answer:
D) above all
Question 13.
The gas releases when electricity is passed through water
A) oxygen
B) hydrogen
C) both A and B
D) A or B
Answer:
C) both A and B
Question 14.
Who had shown that if electrodes were immersed in water and a current was passed, bubbles of oxygen and hydrogen were produced ?
A) William Nicholson
B) William Nicol
C) Antoine Lavoisier
D) None
Answer:
A) William Nicholson
Question 15.
The passage of an electric current through a conducting solution causes
A) bubbles at electrodes
B) chemical effect
C) both A and B
D) none
Answer:
C) both A and B
Question 16.
When electricity is passed through water ……………….. bubbles formed on the electrode connected to the positive terminal of the battery.
A) oxygen
B) hydrogen
C) both A and B
D) A or B
Answer:
A) oxygen
Question 17.
The gas releases when electricity is passed through water
A) oxygen
B) hydrogen
C) both A and B
D) A or B
Answer:
C) both A and B
Question 18.
The ……………….. colour spot appears when electricity is passed through the potato.
A) yellowish red
B) greenish blue
C) black and white
D) violet
Answer:
B) greenish blue
Question 19.
The greenish blue colour spot appears at …………….. terminal when electricity is passed through the potato.
A) positive
B) negative
C) both A and B
D) A or B
Answer:
A) positive
Question 20.
Which of the following is not an application of electroplating ?
A) rold gold jewellery
B) chromium coating on cycle handles
C) nickel coating on taps
D) painting on iron grills
Answer:
D) painting on iron grills
Question 21.
When electric current is passed through the copper sulphate solution, copper sulphate dissociates into ……………………… .
A) copper and carbon
B) copper and oxide
C) copper and sulphate
D) copper and hydrogen
Answer:
C) copper and sulphate
Question 22.
When electric current is passed through the copper sulphate solution, free copper deposits on the …………………. terminal.
A) positive
B) negative
C) A or B
D) on both positive and negative
Answer:
B) negative
Question 23.
The process of depositing a layer of any desired metal on another material by means of electricity is called
A) electroplating
B) electrolysis
C) photoelectric
D) electromagnetism
Answer:
A) electroplating
Question 24.
Generally …………………… plating is done on many objects such as car parte, bath taps, kitchen gas burners, bicycle handlebars, wheel rims and many others.
A) chromium
B) carbon
C) zinc
D) tin
Answer:
A) chromium
Question 25.
Property of Chromium is
A) shiny appearance
B) does not corrode
C) resists scratches
D) above all
Answer:
D) above all
Question 26.
…………… cans, used for storing food, are made by electroplating.
A) Chromium
B) Carbon
C) Zinc
D) Tin
Answer:
D) Tin
Question 27.
Coating of ………………… on Iron is used in bridges and automobiles to provide strength.
A) chromium
B) carbon
C) zinc
D) tin
Answer:
C) zinc
Question 28.
In the electroplating factories the disposal of the used ………………. is a major concern.
A) conducting solution
B) electricity
C) depositing metal
D) electrodes
Answer:
A) conducting solution
Question 29.
Rold gold jewellery are made in the process of
A) electroplating
B) electrolysis
C) photoelectric
D) electromagnetism
Answer:
A) electroplating
Question 30.
Identify the poor conductor among the following.
A) Salt solution
B) Sugar solution
C) Base
D) Acid
Answer:
B) Sugar solution
Question 31.
Prem set up an experiment as shown below.
He found that the bulb glowed. Which of the following actions would result in the bulb NOT glowing ?
A) Adding a few drops of sulphuric acid to the salt water
B) Replacing the carbon rods with copper plates
C) Dropping some metal coins into the salt water
D) Replacing the salt water with distilled water
Answer:
D) Replacing the salt water with distilled water
Fill in the blanks.
1. Some liquids are good conductors of electricity and some are …………………. . conductors.
Answer:
poor
2. Most liquids that conduct electricity are solutions of …………………. .
Answer:
acids, bases and salts
3. The passage of an electric current through a conducting liquid causes chemical reactions. The resulting effects are called …………………. of currents.
Answer:
chemical effects
4. The process of depositing a layer of any desired metal on another material, by means of electricity, is called ………………… .
Answer:
electroplating
5. LED means ………………….
Answer:
Light Emitting Diode
6. Jewellery makers electroplate silver and gold on …………………. expensive metals.
Answer:
less
Match the following.
Question 1.
Match the following and choose the correct option.
Group – A | Group – B |
i) Poor conductor | a) milk |
ii) Good conductor | b) silicon |
c) pure water |
Answer:
i – c, ii – a
Group – A | Group – B |
i) Poor conductor | a) milk |
ii) Good conductor | c) pure water |
Question 2.
Match the following and choose the correct option.
Group – A | Group – B |
i) Chromium | a) cycle handle bars |
ii) Tin | b) food storage cans |
c) air |
Answer:
i – a, ii – b
Group – A | Group – B |
i) Chromium | a) cycle handle bars |
ii) Tin | b) food storage cans |
Question 3.
Match the following and choose the correct option.
Group – A | Group – B |
i) Chemical effect | a) electroplating |
ii) Heating effect | b) electromagnet |
c) electric bulb |
Answer:
i – a, ii – c
Group – A | Group – B |
i) Chemical effect | a) electroplating |
ii) Heating effect | c) electric bulb |