CBSE Class 8 Science Worksheet
Chemical effects of Electric Current
1.
Choose the correct answer: The process of depositing a thin layer of desired metal on another metal is called ____________.
A)
Anodizing
B)
Electroplating
C)
Galvanization
D)
None of these
2.
Fill in the blanks: ___________ is connected to the positive terminal of a battery.
3.
Fill in the blanks: Electroplating is used to give more ___________ to the cheap objects.
4.
State True or False: Tin is more reactive than iron.
A)
true
B)
false
5.
Why is tin electroplated on iron for making cans used for storing food?
6.
Choose the correct answer: The device which is used to show the deflection because of electric cuurent is _______________.
A)
Ammeter
B)
Voltmeter
C)
Ohmmeter
D)
Galvanometer
7.
Choose the correct answer: What metal is used as a cathode in common dry cell?
A)
Sodium
B)
Copper
C)
Tin
D)
Zinc
8.
State True or False: Curd water is a good conductor of electricity.
A)
true
B)
false
9.
Fill in the blanks: In ___________ cell , zinc and copper plates are dipped in separate solution.
10.
Choose the correct answer: A metal which is released in the electrolysis of a salt will be deposited on the ____________________.
A)
Anode
B)
Cathode
C)
On the sides of the container
D)
None of these
11.
How conducting properties of substances can be proved when the current is very small and the bulb does not glow?
12.
Fill in the blanks: Small amount of a mineral salt present naturally in water makes it a______________ of electricity.
13.
Which of the following metal is not extracted by electrolysis?
A)
Iron
B)
Copper
C)
Aluminium
D)
Sodium
14.
Choose the correct answer: Two or more cells are joined together to form __________________.
A)
Transformer
B)
Filter
C)
Battery
D)
None of these
15.
Choose the correct answer: Electric current can produce ______________________.
A)
Heating effects
B)
Chemical effects
C)
Magnetic effects
D)
All of these
16.
Choose the correct answer: The decomposition of an electrolyte when electricity is passed through it, is called ________________.
A)
Anodizing
B)
Electroplating
C)
Conduction
D)
Electrolysis
17.
Which substance is produced by the electrolysis of an aqueous solution of sodium chloride?
A)
Sodium carbonate
B)
Sodium bicarbonate
C)
Sodium hydrogen carbonate
D)
Sodium hydroxide
18.
Which of the following has the highest resistance?
A)
Conductor
B)
Insulator
C)
Semi- conductor
D)
None of these
19.
Fill in the blanks: _____________ is the process of depositing a thin layer of another metal like zinc to protect from corrosion.
20.
Which of the following is the poorest conductor of electricity?
A)
Rain water
B)
Air
C)
Sea water
D)
Silicon
CBSE Class 8 Science Worksheet
Chemical effects of Electric Current
Answers
1.
Option C
2.
Anode
3.
shining
4.
Option B
5.
Tin is less reactive than iron. It is non-poisonous and doesn't corrode. Due to tin plating over the surface of the iron, the food does not come in contact with iron and is protected from getting spoiled.
6.
Option D
7.
Option D
8.
Option A
9.
Voltaic
10.
Option B
11.
By the deflection of the magnetic compass.
12.
Conductor
13.
Option A
14.
Option C
15.
Option D
16.
Option D
17.
Option D
18.
Option B
19.
Galvanization
20.
Option B
