Showing posts with label class8-science. Show all posts
Showing posts with label class8-science. Show all posts

Saturday, 28 October 2017

CBSE Class 8 Science - Chemical Effects of Electric Current (Q and A) (#cbseNotes)

Chemical Effects of Electric Current (Q and A)

CBSE Class 8 Science - Chemical Effects of Electric Current (Q and A) (#cbseNotes)

Q1: Which of the following liquids conduct electricity & which do not conduct electricity?
Lemon juice, Milk, Vinegar, Salt solution, Distilled water, Honey, Seawater, Rainwater.

Answer:
Conducting: Lemon juice, Vinegar, Salt solution, sea water, Rainwater
Non-Conducting: Milk, Distilled water, Honey.


Q2: What is an electric current?

Answer: The rate of the flow of charge is called an electric current.


Q3: Name a device which glows even when a weak electric current passes through it.

Answer: LED (Light Emitting Diode)


Friday, 6 October 2017

CBSE Class 8 - Science - Ch 8 - Cell Structure and Functions (Worksheet) (#cbseNotes)


Cell Structure and Functions (Worksheet) 


CBSE Class 8 - Science - Ch 8 - Cell Structure and Functions (Worksheet) (#cbseNotes)


Fill in the blanks

1. ______ is the structural and functional unit of life.


2. All living organisms are made of ______.


3. Cells were first observed by ____________ in 1665.


4. Antonie van Leeuwen hook was the first to see __________ under microscope which he had constructed himself

Saturday, 30 September 2017

CBSE Class 8 Science - Term 1 - Sample Question Paper (2017-18) (#cbsePapers)

SAMPLE PAPER OF SCIENCE FOR Term-1 (2017-18)       

CLASS-VIII
CBSE Class 8 Science - Term 1 - Sample Question Paper (2017-18) (#cbsePapers)
M.M-90                                                                                                              Time: 3 Hrs

General Instructions:
1. The question paper consists of 34 questions and is divided into four sections, A, B, C and D
2. All questions are compulsory.
3. Section A comprises question numbers 1 to 10. Each carries 1 mark
4. Section B comprises question numbers 11 to 20. Each carries 2 marks
5. Section C comprises question numbers 21 to 30. Each carries 3 marks.
6. Section D comprises question numbers 31 to 34. Each carries 5 marks.

SECTION-A  
Q1. Name the process of sowing seeds by scattering them in the field by hand.
Q2. Why are dried neem leaves put in the container in which food grains are stored?
Q3. What is the huge reserve stock of food grains held by government agencies called?
Q4. How is yeast a beneficial fungi?
Q5. Which antibiotic was discovered first and who discovered it?
Q6. Which phenomenon  disturbs the nitrogen cycle?
Q7. Are the handles and bristles of tooth brush made of same material?
Q8. Why are metals used to make bells and musical instruments?
Q9. How does pressure at a point within a liquid change with its depth?
Q10. Why  is a sharp knife more effective in cutting a fruit than a blunt life?

Friday, 29 September 2017

CBSE Class 8 - Science - Ch 18 Pollution Of Air and Water - Chapter Notes (#cbseNotes)

POLLUTION OF AIR AND WATER

(Chapter Notes)
CBSE Class 8 - Science - Ch 18 Pollution Of Air and Water - Chapter Notes (#cbseNotes)

Pollution is release of harmful substances in the environment thus causing threats to our ecosystem. Even non-harmful substances when precipitated in environment can be harmful. Land, water and air are the most important natural resources. Man made factors (agriculture, industrialization, transport etc.) are the primary reasons for the pollution.

According to World Health Organizations, five millions deaths occur in India due to pollution.
Pollution can be classified in many categories like:
  • Land Pollution
  • Air Pollution
  • Water Pollution
  • Noise Pollution
  • Light Pollution
Here we discuss primarily about Air pollution and Water pollution.
Composition of Air
Air is a mixture of gases. 
By volume, Nitrogen:78%, Oxygen:21% and 1% (remaining gases like Carbon Di-oxide, Ozone, Argon, Methane etc.)

Wednesday, 20 September 2017

CBSE Class 8 - Science - Solar System Some Facts (#cbseNotes)

Solar System (Some Facts)

CBSE Class 8 - Science - Solar System Some Facts (#cbseNotes)


• Biggest Planet : Jupiter

• Smallest Planet : Mercury

• Nearest Planet to Sun : Mercury

• Farthest Planet from Sun : Neptune

Sunday, 17 September 2017

CBSE Class 8 - Science - Half Yearly Sample Question Paper (2017-18) (#cbsePapers)

SCIENCE SAMPLE PAPERHALF YEARLY ASSESSMENT (2017-18)CLASS - VIII



CBSE Class 8 - Science - Half Yearly Sample Question Paper (2017-18) (#cbsePapers)


TIME-3 hrs                                                                                                    MM-80 Marks

GENERAL INSTRUCTIONS:-
1. All questions are compulsory.
2. This paper contains 4 sections: namely SECTION A- Physics, SECTION B-Chemistry,
SECTION C- Biology and SECTION D- MCQ
3. Please attempt the questions in serial order.

SECTION A (PHYSICS)

Q1. Fill in the blanks                                        (1x7= 7)
a) If light bends towards the normal as it goes from media A to medium B, then medium A is optically ______ than medium B.

b) For a normal eye, the ________ point is infinity.

c) A ______ is an instrument used in submarines to view objects on the surface of the sea.

d) The ______ constellation forms the shape of a hunter.

e) ______ was the first satellite sent up from the earth.

f) The galaxy we live in is called the __________.

g) ______ is the distance between the optical centre and the focus of a lens.


Friday, 8 September 2017

CBSE Class 10 - Light - Reflection From Mirrors (Worksheet) (#cbseNotes)

Light - Reflection From Mirrors (Worksheet)

CBSE Class 10 - Light - Reflection From Mirrors (Worksheet) (#cbseNotes)



1. We get a diminished image with a concave mirror when the object is placed ____.


2. The drivers mirror used in automobiles is ____.


3. The distance of focus F from the pole P is termed as the ..................... of the mirror.


4. Mirror formula is ____.


Sunday, 3 September 2017

CBSE Class 8 - Physics - Force and Pressure, Friction and Universe (Revision Sheet) (#cbseNotes)

Physics - Force and Pressure, Friction and Universe (Revision Sheet)

CBSE Class 8 - Physics - Force and Pressure, Friction and Universe (Revision Sheet) (#cbseNotes)

1. What is the necessity of pressurized cabins and airplanes?

2. You are provided with two surfaces, one smooth and one rough or uneven. Try to stick a rubber sucker on both the surfaces. Will you succeed in doing so? Give reasons for your answer.

3. Can a scuba diver dive into the ocean wearing ordinary clothes? Why or why not?

4. Why do some people experience nasal bleeding at high altitudes?

5. Explain Why, it is easier to drag a mat on floor when nobody is sitting on it but much more difficult to drag the same mat when a person is sitting on it.

6. Name the type of force in the following cases.

(a) Force exerted between heavenly bodies.
(b) Force to pull a heavy object.
(c) Force that slows down moving objects.
(d) Force due to charged particles.

Wednesday, 30 August 2017

CBSE Class 10 - Chemistry - Metals and Non-Metals - Alloys Their Compositions and Uses (#cbseNotes)

Alloys - Compositions, Properties and Uses

CBSE Class 10 - Chemistry - Metals and Non-Metals - Alloys Their Compositions and Uses (#cbseNotes)


Steel
Components: Iron, Carbon

Properties: Hard and Strong

Uses:
- Construction of buildings and bridges,
- manufacture of ships
- manufacture of spare parts for automobiles






Tuesday, 29 August 2017

CBSE - Class 8 - Science - Friction (Assignment Sheet) (#cbseNotes)

FRICTION - WORKSHEET


Class 8 - Physics


Multiple Choice Questions (1-10)


1. It is difficult to walk on any oily floor because
a) Floor gets spoiled
b) There is more resistance
c) Force of friction is high
d) Force of friction is very less


2. Spring balance is a device used for measuring the _____________ acting on an object.
a) mass
b) pressure
c) force
d) None of the above

3. A matchstick struck on a matchbox catches fire easily because
a) Friction may cause fire
b) Of chemical reaction
c) Force heated the match stick
d) None of the above

Monday, 28 August 2017

CBSE Class 10 / class 8 - Science - About Human Eye (#cbseNotes)

About Human Eye - Questions and Answers

CBSE Class 10 / class 8 -  Science - About Human Eye (#cbseNotes)


Human eye can be considered as an optical instrument. Light rays coming from the object to be seen enter the eye through Cornea and fall on the eye lens through the pupil of the eye.



Parts of the human eye are:


Cornea:
The transparent spherical membrane covering the front of the eye.

Sunday, 27 August 2017

CBSE Class 8 - Science - Force and Pressure- Assignment (#cbseNotes)

CBSE Class 8 - Science - Force and Pressure- Assignment (#cbseNotes)

CBSE Class 8 - Science - Force and Pressure- Assignment

Practice Sheet for Science chapter on Force and Pressure (NCERT Class 8)






CBSE Class 8 - Science - Sound Assignment (#cbseNotes)

CBSE Class 8 - Science - Sound Assignment (#cbseNotes)

CBSE Class 8 - Science - Sound Assignment

Practice Sheet for Science chapter on Sound (NCERT Class 8)






Saturday, 26 August 2017

CBSE Class 8 - Science - Metals and Non-Metals (Question Bank) (#cbsenotes)

Metals and Non-Metals (Question Bank)


CBSE Class 8 - Science - Metals and Non-Metals (Question Bank) (#cbsenotes)


Name the following questions:
1. Name some common non-metals used in our daily life.

2. Hardest naturally occurring substance.

3. Property of metals which make them useful as electric wires.

4. Non – metal which has metallic luster.

5. Two non metals which are soft solids.

6. Non metals do not conduct electricity or heat except for one . Name it.

7. An allotrope of carbon which is as tensile as steel.