Class 8 Chemical Effects Of Electric Current CBSE Questions & Answers

Class 8 · Chemical Effects Of Electric Current

This is Science Class 8 Chemical Effects of Electric Current CBSE Questions & Answers. There are 15 questions in this test with each question having around four answer choices.

Questions & Answers

1
Which of the following substance should not be added to distilled water to make it good conductor?
  • A
    Acids
  • B
    Salts
  • C
    Alcohol
    Correct
  • D
    Bases
2
A device that converts the electrical energy into heat energy is
  • A
    Fan
  • B
    Motor
  • C
    MP3
  • D
    Heater
    Correct
3
Jewellery maker electroplate silver and gold on less expensive metals to make it
  • A
    To make it corrosion free
  • B
    To increase the cost of jewelleries
  • C
    To make it resistance to corrosion
  • D
    To have the appearance of silver and gold
    Correct
4
What serve as cathode in common dry cell?
  • A
    Zinc container
    Correct
  • B
    Carbon electrode
  • C
    Nickel container
  • D
    Steel cover
5
Which type of tester is most suitable for testing flow of very low current?
  • A
    Magnetic needle type
    Correct
  • B
    Solution type
  • C
    LED type tester
  • D
    Incandescent bulb type
6
What is the common name for manganese-dioxide-alkaline-zinc cell?
  • A
    Moz cell
  • B
    Manganese-dioxide
  • C
    Long life cell
  • D
    Alkaline cell
    Correct
7
The two leads of LED is are of
  • A
    Joined together
  • B
    Any one
  • C
    Unequal length
    Correct
  • D
    Equal length
8
During refining of metal
  • A
    Thick sheet of pure metal
  • B
    Thin impure metal
  • C
    Thin sheet of pure metal
    Correct
  • D
    Thick Impure metal
9
When iron nail is placed in Blue colored solution of copper sulphate it change to green due to
  • A
    Addition reaction
  • B
    Decomposition reaction
  • C
    Displacement reaction
    Correct
  • D
    Combination reaction
10
It is not safe to carry out electrical repair works outdoor during rain because
  • A
    All of these
  • B
    Rain water is good conductor of electricity
    Correct
  • C
    It become difficult to grips the tools
  • D
    Rain cause lowering of temperature
11
Which property of LED makes it more popular as source of light?
  • A
    It looks very attractive and colourful
  • B
    It is available in many colours and shapes
  • C
    It consume less electricity and last longer
    Correct
  • D
    It is available in market at very low cost
12
Which of the following is concern over the use of CFL
  • A
    It is less durable
  • B
    It is very costly
  • C
    It contain mercury which is toxic
    Correct
  • D
    It can not be used everywhere
13
Rain water and distilled water are bad conductor of electricity but rain water sometimes conduct electricity due to
  • A
    Absence of salts in rain water
  • B
    Presence of base in rainwater
  • C
    Presence of oxygen gas in water
  • D
    Presence of acid due to pollution
    Correct
14
Which type of tester is most suitable for testing flow of very low current?
  • A
    Solution type
  • B
    LED type tester
  • C
    Incandescent bulb type
  • D
    Magnetic needle type
    Correct
15
Which type of effect is produced by electric current passes through a conducting solution?
  • A
    Magnetic effect of electric current
  • B
    Physical effect of electric current
  • C
    Heating effect of electric current
  • D
    Chemical effect or electric current
    Correct