The important questions for CBSE class 8 Science are prepared by subject experts according to the latest syllabus of CBSE. Students are advised to solve these important questions which can make them more focused on their exam and also bring a sense of discipline and seriousness in their exam preparation. The Central Board of Secondary Education (CBSE) is a prestigious educational board which comes under the Union Government of India. Here, you will get the clue that from where and how the questions are being framed from the chapter Chemical Effects of Electric Current for CBSE Class 8 Science. These questions can provide students a chapter wise preparation strategy so that they can prepare for their exam more efficiently.

The National Council of Education and Training sets the curriculum for all schools that follow the Central Board of Secondary Education (CBSE) across the nation. The important questions provided below will also make students familiar with the marking scheme and the difficulty level of the exam.

This question paper is designed based on the academic syllabus. Sample papers should be practiced in examination condition at home or school and also show it to your teachers for checking or compare with the answers provided. Creative questions were added in this question paper in order to enhance the student's knowledge and get the idea that how to answer strategic questions asked in the board exams.

Download CBSE Class 8th Standard CBSE Science question papers, sample papers, important questions, and previous year solved papers in PDF format. Get free study materials, NCERT solutions, and exam preparation resources for Class 8th Standard CBSE Science

Questions:

Generic 3

5 x 3 = 15

Last Wednesday, Suhail woke up late in the morning. So, he saw the time and suddenly realised that he got late for an interview, which he was supposed to give after reaching the venue by the right time. Immediately, he turned on the geyser but it did not work. He got more tensed, then he used an electric iron rod through which he got some boiled water for his bath. Actually, there was an earthing problem in the switch board about which he was unaware. He was barefooted and was just about to switch on the electric iron rod but was restricted to do so by his room partner living with him. It could be dangerous for Suhail.
(i) Explain in brief what could have happened with Suhail if he had switched on the electric iron rod barefooted.
(ii) Mention the values showed by Suhails room partner.

Paheli wants to deposit silver on an iron spoon. She took silver nitrate (AgNO₃) solution in a beaker and set up a simple circuit for electroplating. Which terminal of the battery should the spoon be connected to? What material should the other electrode be made of?

An electric current is passed through a conducting solution. List any three possible observations.

Boojho made the circuit as shown in figure. He wanted to observe what happens when an electric current is passed through water. But he forgot to add a few drops of lemon juice to water. Will it make any difference to his observations? Explain

Name three liquids which when tested in the manner shown in figure below may cause the magnetic needle to deflect.

Generic 2

5 x 2 = 10

Can some fruits and vegetables conduct electricity? Explain with an example

A tester is used to check the conduction of electricity through two liquids, labelled A and B. The bulb of tester glows very brightly for liquid A. It is found that the bulb of the tester glows very dimly for liquid B. Which liquid is better conductor of electricity?

Why is tin electroplated on iron to make cans used for storing food?

When a compass needle is brought near a current carrying wire, then what happens?

10.

Will the solution of sugar in distilled water conduct electricity?

Generic 5

3 x 5 = 15

11.

Observe the circuit given in figure.

Boojho set up this circuit for purification of copper. What will be the nature of
(a) plate A
(b) plate B
(c) and the solution. Explain the process of purification

12.

You are provided with a magnetic compass, an empty matchbox, a battery of two cells and connecting wires. Using these objects, how will you make a tester for testing an electric circuit? Draw the necessary circuit diagram and explain.

13.

In the circuit given in the figure, Boojho observed that copper is deposited on the electrode connected to the negative terminal of the battery. Paheli tried to repeat the same experiment. But she could find only one copper plate. Therefore, she took a carbon rod as negative electrode. Will copper be still deposited on the carbon rod? Explain your answer.

Multiple Choice Question

5 x 1 = 5

14.

Which of the following metals is used in electroplating to make objects appear shining?

(a)

Iron

(b)

Copper

(c)

Chromium

(d)

Aluminium

15.

Boojho's uncle has set up an electroplating factory near his village. He should dispose off the waste of the factory

(a)

in the nearby river

(b)

in the nearby pond

(c)

in the nearby corn field

(d)

according to the disposal guidelines of the local authority

16.

Which of the following solutions will not make the bulb glow in figure?

(a)

Sodium chloride

(b)

Copper sulphate

(c)

Silver nitrate

(d)

Sugar solution in diluted water

17.

Which one of the following solutions will not conduct electricity

(a)

Lemon juice

(b)

Vinegar

(c)

Tap water

(d)

Vegetable oil

18.

When electric current is passed through a conducting solution, there is a change of colour of the solution. This indicates

(a)

the chemical effect of current

(b)

the heating effect of current

(c)

the magnetic effect of current

(d)

the lightning effect of current

Fill up / 1 Marks

3 x 1 = 3

19.

Small amount of a mineral salt present naturally in water makes it a.......of electricity

20.

One of the most common applications of chemical effect of electric current is..........

21.

The object to be electroplated is taken as.........electrode

1 Marks

2 x 1 = 2

22.

What is the ill effect of electroplating?

23.

Give two examples of good conductors.

Visit QB365-SLMS - https://www.qb365.in/slms/

Answers Key:

Generic 3

5 x 3 = 15

(i) If Suhail had switched on the electric iron rod barefooted, then he could have met with some accident, either in the form of electrical sparking or short circuit of switch board.
(ii) Suhail's room partner seems to be very intelligent and very much concerned for Suhail as well.

Spoon should be connected to the negative terminal of the battery. The other electrode should be of silver so that silver ions get deposited on an iron spoon.

Three possible observations are
(i) The colour of the solution may change depending upon the electrodes.
(ii) The temperature of the solution may increase.
(iii) Bubbles near the electrodes can be seen.

Adding few drops of lemon juice in water will increase the conductivity of the solution. The current will flow in both the cases but adding of lemon juice makes easy the current to flow.

The three liquids are as follows:
(i) Tap water
(ii) HCI or hydrochloric acid
(iii) Sodium hydroxide

Generic 2

5 x 2 = 10

Some fruits and vegetables also conduct electricity. It is explained with the following example

(i) Cut a potato into two halves.
(ii) Insert the copper wires of a tester into it.
(iii) Keep it for an hour.
(iv)There appears a greenish blue spot on the potato around the wire.
(v) It is because the current produces a chemical effect on potato.
(vi) Hence, it is clear that vegetables conduct electricity

Liquid A is better conductor of electricity because it can pass the electricity very easily due to which bulb glows very brightly.

Electroplating is done on the iron to prevent it from rust and corrosion and it is cheap.

When a compass needle is brought near a current carrying wire, then needle deflects.

10.

The sugar solution in distilled water will make it a good conductor of electricity and current can easily pass through it.

Generic 5

3 x 5 = 15

11.

We take CuS04 solution and dip a pure copper plate as cathode (-ve) and impure copper plate as anode (+ve). Due to voltage of battery, the impurities from the impure sample slowly deposit at the bottom and the copper plate becomes purified .

12.

Take the tray from the inside of a discarded matchbox. Wrap an electric wire a few times around the tray. Place a small compass needle inside it. Now connect one free end of the wire to the one terminal of a battery. Leave the other end free.
Take another piece of wire and connect it to the other terminal of the battery. Join the free ends of two wires momentarily. The compass needle should show deflection. Your tester with two free ends of the wire is ready.

13.

Copper will not be deposited on the carbon rod because carbon rod is a poor conductor of electricity. For electroplating, the circuit must be completed and that can be completed only by using the conducting material. Instead of carbon rod, it should be any metal, then only it can be electroplated.

Multiple Choice Question

5 x 1 = 5

14.

15.

(d)
according to the disposal guidelines of the local authority

16.

(d)
Sugar solution in diluted water

17.

(d)
Vegetable oil

18.

(a)
the chemical effect of current

Fill up / 1 Marks

3 x 1 = 3

19.

()
good conductor

20.

()
electroplating

21.

()
negative

1 Marks

2 x 1 = 2

22.

()
The used conducting solution causes pollution

23.

()
Silver, copper.

Important Questions from Chemical Effects of Electric Current - 8th Science

QB365 Student Learing Managemnet System

Std: 8th Standard CBSE - Science

chapter: - Model Question paper

Visit QB365-SLMS - https://www.qb365.in/slms/ Complete Questions and Answers

Questions:

Visit QB365-SLMS - https://www.qb365.in/slms/

Answers Key:

NEW MCQ Practice Test - CBSE Class 8

Science CBSE Class 8 MCQ Practice Test

CBSE Class 8 MCQ Practice Test

8th Standard CBSE Study Materials