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Showing posts with label class8-science. Show all posts
Showing posts with label class8-science. Show all posts
Friday 10 March 2017
Monday 27 February 2017
Wednesday 14 December 2016
CBSE Class 8 - Science - REACHING THE AGE OF ADOLESCENCE
REACHING THE AGE OF ADOLESCENCE
Q & A Based NCERT Class 8 Science Chapter
Q 1: List the changes occur during adolescent age.
Answer:
CHANGES OCCUR AT ADOLESCENT AGE:
1) INCREASE IN HEIGHT
2) DEVELOPMENT OF HAIR
3) SEXUAL FEELING
4) VOICE CHANGES
5) CHANGE IN BODY SHAPE
6) CHANGE IN BEHAVIOUR AND ATTITUDES
7) ACTIVITY OF SWEAT AND OIL GLANDS
Q 2: What is the function of endocrine system? What is it made up of?
Answer: There are a number of other slower processes that go on in the body, such as growth such processes are primarily controlled by the endocrine system.
The endocrine system consist of a number of ductless glands that secrete hormones.
Q3: What is Adam's apple?
Answer: Adam's apple: The protruding part of the throat is called Adam’s apple. It is the enlarged voice box or larynx which gets enlarged and visible from outside in boys at the onset of puberty. This makes the voice of boys hoarse.
Q 4: Name four body processes that hormones control?
Answer: Growth behavior, development and reproduction are controlled by hormones.
Friday 30 September 2016
Class 8, 10: Science - Uses of Some Common Metals and Non-Metals
Uses of Some Common Metals and Non-Metals
USES OF SOME COMMON METALS
Metal | Main Uses |
---|---|
Iron | Bridges, Train tracks, Construction Bars, Steel, Engine Parts, Iron sheets etc. |
Copper | Electrical Wires, Utensils, Coins etc. |
Aluminium | Electric Wires, Utensils, Airplanes, Metallic Paints, Foil for packaging etc. |
Silver | Jewellery, Electroplating, photography, Utensils, Coins, silvering of mirrors etc. |
Gold | Jewellery and Decorations, Coins |
Lead | Batteries, Alloys, Paints, Alloys like solder, Protective screen for X-Rays etc. |
Mercury | Thermometers, Barometers, Dental amalgams etc. |
Friday 15 July 2016
CBSE Class 8 - Science - COMBUSTION AND FLAME (HOTS Questions and Answers)
COMBUSTION AND FLAME
Forest Fires - Why do forests catch fire in hot summers? |
HOTS Q & A (Class 8 Living Science Textbook Chapter Solutions)
Q1: Only gases burn with a flame. When you burn wood it initially burns with a flame. Later it only glows without a flame. What do you think the answer is?
Answer: Wood contains many chemicals like resin, lignin. When heated, these chemicals broke up and release combustible gases. That's why wood burns initially with a flame. When these gases are exhausted, wood burns without flame.
Q2: Would you consider coal as a good fuel? Give reasons?
Answer: Coal is not considered as a good fuel because of the following reasons:
1. It has low calorific value as compared to Petroleum and LPG.
2. On burning it releases many polluting gases like CO2 which is a green house gas and it causes global warming.
3. Coal contains traces of Sulphur and Nitrogen which on burning gives harmful gases like Nitrogen Oxide and Sulphur Oxide. These gases when mixed with rain water cause acid rain.
4. Unburnt traces of carbon also causes respiratory problems.
Q3: When a fuel is burnt, carbon dioxide (or carbon monoxide) and water vapour are given out. Can you name one fuel which burns without giving off water vapour? Why does it not give out water?
Answer: Charcoal is pure form of carbon. When it burns with oxygen, it forms carbon dioxide and no waters vapours are given off.
Q4: Why does a matchstick burn on rubbing it on the side of the match box?
Answer: Matchstick uses chemicals like phosphorus which has low ignition temperature (35°C). When the stick is rubbed, due to friction heat is generated which is sufficient to raise temperature to above 35°C and ignites the stick.
Sunday 3 July 2016
CBSE Class 8 - Science - MICROORGANISMS AND VIRUSES – Friends and Foes! (Q and A)
MICROORGANISMS AND VIRUSES – Friends and Foes!
(Chapter Solutions of textbook Prachi Science for Class 8)
Fungal Infected Bread |
Q1. Answer in one word.
1. Name two typical habitats of micro-organisms
Answer: Commonly found everywhere – in the air, in water, inside the bodies of living organisms.
2. Name a disease caused by bacteria
Answer: Tuberculosis, Pneumonia
3. Name the microorganism that is used for obtaining alcohol from sugar.
Answer: Yeast.
4. Name one carrier of disease-causing microorganisms.
Answer: House Fly which causes many diseases like cholera, typhoid, diarrhoea.
5. Where do the external parasites of animals live?
Answer: External parasites like lice, flies, ticks, grubs etc. live on the skins of the animals.
Q2. Short- Answer Questions (10-15 words)
Saturday 14 May 2016
CBSE Class 8 - Science - METALS and NON Metals : Question and Answers
METALS and NON Metals :
Question and Answers
Prachi Class 8 Science Textbook Solutions
Activity Series |
Q1: Identify the type of elements which are neither malleable nor ductile.
Answer: Non-metals (eg Carbon, Phosphorous, Sulphur, Nitrogen) are neither malleable nor ductile.
Q2: Name a property which is common to the metals occurring near the bottom of the reactivity series.
Answer: These (Silver, Gold and Platinum) are least reactive metals and are found in free state in the earth's crust.
Q3: Name a metal that is kept under kerosene.
Answer: Sodium.
Q4: What type of reaction is the reaction between copper sulphate solution and zinc plate?
Answer: It is a displacement reaction.
Zn + Copper Sulphate ---------> Zinc Sulphate + Copper
(Explanation: Zinc is more reactive than copper, Therefore Zn displaces Cu.)
Q5: An oxide of sulphur turns blue litmus red. Is it acidic or basic?
Answer: Acidic
Sunday 24 April 2016
CBSE Class 8 - Living Science (CCE Edition) : Crop Production (Text Book Answers)
Living Science (CCE Edition) : Crop Production
Textbook Answers
Multiple Choice Questions (pg 20)
Q: Which of these is not a cereal?...
Answers:
1: (a) Gram
Explanation: Gram is a legume (pulses) while others are cereals
2: (a) Wheat
Explanation: Wheat is a rabi (winter) crop.
3: (a) organic nutrients
Explanation: Compost is made of dead and decaying organic matter.
4: (a) Wilt
Explanation: Wilt is caused by bacteria while others are fungal infections.
5: (c) it prevents soil erosion.
Explanation: Ploughing loosens soil so that more air can fill up the spaces.
6: (d) All of these
7: (d) ploughing
Explanation: Manuring or Fertilizers or Field Fallowing add nutrients.
8: (b) Combine
VERY SHORT ANSWER QUESTIONS (One word answers) - Pg 20-21
Q1. About how many years ago did agriculture begin?...
Tuesday 8 March 2016
CBSE Class 8 - Science - Chapter 1 - Crop Production and Management (Questions and Answers)
Crop Production and Management
Types of Crops (based on Seasons) |
Questions and Answers based on Class 8 NCERT Chapter
Q1: Define agriculture.
Answer: It is a science that deals with the growth of plants and animals for human use is called agriculture.
Answer: When plants of the same kind are grown and cultivated at one place on a large scale, it is known as a crop. For example, crop of wheat means that all the plants grown in a field are that of wheat.
Answer: All the activities which are involved in the cultivation of crops from sowing to harvesting are known as agricultural practices.
Answer: Following are the reasons that India need improved agricultural practices:
i. India's population is around 1.20 Billion and it is growing faster than its ability to produce wheat and rice.
ii. To provide sufficient food to such a large population, it is required to maintain regular production and proper crop management.
iii. It requires an improvement in agricultural practices and application of latest technology.
Q5: List the seven agricultural practices.
Answer:
i. Preparation of soil
ii. Sowing
iii. Adding manure and fertilisers
iv. Irrigation
v. Protecting from weeds
vi. Harvesting
vii. Storage
Answer: It is a science that deals with the growth of plants and animals for human use is called agriculture.
Q2: Define Crop
Answer: When plants of the same kind are grown and cultivated at one place on a large scale, it is known as a crop. For example, crop of wheat means that all the plants grown in a field are that of wheat.
Q3: What are agricultural practices?
Answer: All the activities which are involved in the cultivation of crops from sowing to harvesting are known as agricultural practices.
Q4: Why does India need improved agricultural practices?
Answer: Following are the reasons that India need improved agricultural practices:
i. India's population is around 1.20 Billion and it is growing faster than its ability to produce wheat and rice.
ii. To provide sufficient food to such a large population, it is required to maintain regular production and proper crop management.
iii. It requires an improvement in agricultural practices and application of latest technology.
Q5: List the seven agricultural practices.
Answer:
i. Preparation of soil
ii. Sowing
iii. Adding manure and fertilisers
iv. Irrigation
v. Protecting from weeds
vi. Harvesting
vii. Storage
Monday 29 February 2016
CBSE Class 8 - Science - Chapter 8 - Cell Structure and Functions (Q and A)
Cell Structure and Functions
Questions and Answers based on NCERT Chapter
Q1: Define Cell
Answer: Cell is the basic structural and functional unit of life.
Q2: Who was the first person to see the cell?
Answer: Robert Hooke, who was the first person to see the cell, in 1665 observed slices of cork under a simple magnifying device.
Q3: What is cork made up of?
Answer: It is a part of the bark of a tree and is made of dead cells.
Q4: Can we see cells with unaided eye?
Answer: Usually animal and plant cells are so small that these can't be seen by the unaided eye. We need a microscope to observe cells. There are few exceptions like hen's egg cell or ostrich's egg which is made up of one large cell that can be seen by an unaided eye.
Q5: Name the largest cell.
Answer: Ostrich's egg.
Q6: What does "cellula" mean in Latin?
Answer: It means a small chamber.
Q7: Name the scientist who discovered nucleus of the cell?
Answer: Robert Brown
Thursday 12 November 2015
CBSE Class 8 - Science Ch 13 - Sound (Worksheet)
Sound
Worksheet
Prolonged Use of Headphones and loud music can make you deaf |
Write True or False for the senses given below. Also rewrite the false statements correctly:
1. Sound is a mechanical wave.
______________________________________________________
2. Sound can travel through vacuum.
_______________________________________________________
3. Sound is produced by a vibrating body.
_______________________________________________________
4. The maximum displacement of a body from its mean position is called amplitude of oscillation.
________________________________________________________
5. Loudness of a sound is measured in Hertz.
_______________________________________________________
Sunday 18 October 2015
CBSE Class 8 - Science - CH 15 - Some Natural Phenomena (Worksheet)
Some Natural Phenomena
Tsunami hits at San Jose: picture by Angela Riddock |
Worksheet based on Class 8 NCERT Chapter 15
Fill in the blanks with appropriate words given below:
seismograph, Ritcher scale, static, earthquake, positive, earthing, thunder, Like charges, seismic waves, unlike charges, electroscope
1. _______ electricity consists of electric charges which do not flow.
2. A glass rod when rubbed with a piece of silk cloth gets charged with ________ charge.
3. Seismic waves are recorded by an instrument called ____________.
4. An explosive sound heard during lightning is termed as _________.
5. _____ _______ repel each other while ______ _______ attract each other.
Sunday 30 August 2015
CBSE Class 8 - Science - CH 17 - Very Short Question Answers on Solar System
Very Short Question on Solar System
VSQ Based on NCERT Chapter 17 on Stars and Solar System
Solar System Grid image courtesy: pixabay |
Q1: Name the biggest planet.
Answer: Jupiter
Q2: Name the smallest planet in our solar system.
Answer: Mercury
Q3: Name the natural satellite of the Earth.
Answer: Moon.
Q4: Which is the nearest planet from the sun?
Answer: Mercury
Q5: Which is the farthest planet from the sun?
Answer: Neptune
Sunday 31 May 2015
CBSE Class 8 - Science - CH 16 - Light (MCQ)
Light
MCQs
Laws Of Reflection credits:wikipedia |
Q1: Image formed by the plane mirror is:
(a) Always real
(b) Always virtual
(c) Sometimes real sometimes virtual
(d) None of these
Q2: The light ray, which strikes any surface, is called:
(a) Reflected Ray
(b) Normal
(c) Incident Ray
(d) Refracted Ray
Q3: The ray that comes back from the surface after reflection is called:
(a) Reflected Ray
(b) Normal
(c) Incident Ray
(d) Refracted Ray
(a) Reflected Ray
(b) Normal
(c) Incident Ray
(d) Refracted Ray
Q4: Which of the following statement is correct:
(a) Angle of incidence is never equal to angle of reflection.
(b) Angle of incidence is always greater than angle of reflection.
(c) Angle of incidence is always smaller than angle of reflection.
(d) Angle of incidence is always equal to angle of reflection.
(a) Angle of incidence is never equal to angle of reflection.
(b) Angle of incidence is always greater than angle of reflection.
(c) Angle of incidence is always smaller than angle of reflection.
(d) Angle of incidence is always equal to angle of reflection.
Q5: The property of plane mirror to make 'right appear as left' and vice versa, is called:
Sunday 26 April 2015
CBSE Class 8 Science - CH 14 - Chemical Effects of Electric Current (MCQs)
Chemical Effects of Electric Current
MCQsQ1: The liquid will conduct electric current in a circuit when the vessel is filled with _________.
(a) distilled water
(b) salt solution
(c) air
(d) helium
Q2: Which of the following substance is not a good conductor of electricity?
(a) copper
(b) aluminium
(c) rubber
(d) mercury
Q3: The decomposition of liquid compound on passing an electric current though it is known as ______
(a) electroplating
(b) electrolysis
(c) magnetic effect
(d) electro-resistivity
Q4: The glowing of filament bulb is due to
Friday 24 October 2014
CBSE Class 6-12 - Science - Fathers in Biology
℉α⊥нεяṧ ◎ḟ Ⅴαґḯøü﹩ ℬґαηḉℌ℮ṧ їη ℬїøł☺ℊ¥
Fathers of Various Branches in Biology
Aristotle - Father of Biology credits: wikipedia |
Num. | Branch of Biology | Name |
1 | Father of Biology | Aristotle |
2 | Father of Zoology | Aristotle |
3 | Father of Botany | Theophrastus |
4 | Father of Taxonomy | Carl Linnaeus |
5 | Father of Plant Physiology | Stephen Hales |
6 | Father of Bacteriology | Louis Pastuer |
7 | Father of Microbiology | Leeuwenhoek |
8 | Father of Immunology | Edward Jenner |
9 | Father of Cytology | Robert Hooke |
10 | Father of Mycology | Micheli |
11 | Father of Genetics | G J Mendel |
12 | Father of Experimental Genetics | T. H. Morgan |
13 | Father of Bryology | Johann Hedwig |
14 | Father of Eugenics | Francis Galton |
15 | Father of Microscopy | Marcello Malphigi |
16 | Father of Bio-diversity | E.O. Wilson |
17 | Father of Medicine | Hippocrates |
18 | Father of modern Anatomy | Andreas Vesalius |
19 | Father of Radiation Genetics | H. J. Muller |
Thursday 21 August 2014
CBSE Class 8 - Science - Ch 13 - Sound (MCQs)
Sound
MCQsQ1: In dholak sound is produced due to ...
(a) stretched membrane
(b) stretched strings
(c) air column
(d) vibration of air
Q2:The pitch of sound depends on the __________ of the vibrating body.
(a) amplitude
(b) noise
(c) frequency
(d) medium of propagation
Q3: Speed of sound in solids is ______ the speed of sound in liquids.
(a) same as
(b) greater than
(c) less than
(d) sometimes greater and sometimes less than
Q4: The human ear can hear sounds having frequency in range ...
(a) between 200 - 20,000 Hz
(b) between 20 - 2000 Hz
(c) between 200 - 2000 Hz
(d) between 20 - 20,000 Hz
Q5: The time taken to complete ___ oscillation(s) is called time period.
Sunday 13 April 2014
CBSE Class 8 - Science - Ch 6 - Combustion & Flame (MCQs)
Combustion & Flame
Combustion & Flame credits:openclipart |
Q1: Which of the following is the chemical process in which a substance reacts with oxygen to give off heat?
(a) Electrolysis
(b) Combustion
(c) Ignition
(d) Friction
Q2: The substance which undergoes combustion is called …
(a) Fuel
(b) Energy
(c) Light
(d) Matter
Q3: Which of the following is not a combustible substance?
(a) Magnesium
(b) Charcoal
(c) Petrol
(d) Glass
Q4: Which of the following has the lowest ignition temperature?
Sunday 23 March 2014
CBSE Class 8 - Science - CH10 - Reaching Age of Adolescence (MCQs)
Reaching Age of Adolescence
Adolescents |
Q1: The period of life when the body undergoes changes, leading to reproductive maturity, is called?
(a) Puberty
(b) Adolescence
(c) Metamorphosis
(d) Menarche
Q2: Onset of sexual maturity in individuals, making them capable of reproduction is termed as _________
(a) Adolescence
(b) Metamorphosis
(c) Puberty
(d) Menarche
Q3: The voice box is also known as __________
(a) Allosomes
(b) larynx
(c) Menarche
(d) Thyroid
Saturday 1 February 2014
CBSE Class 8 - Science - CH9 - Reproduction in Animals (MCQs)
Reproduction in Animals
(MCQs)
Q1: The male gametes are called ...
(a) Ovaries
(b) Sperms
(c) Zygote
(d) Eggs
Q2: The female gametes are called ...
(a) Ovaries
(b) Sperms
(c) Zygote
(d) Eggs
Q3: The female gametes are produced by?
(a) Ovaries
(b) Sperms
(c) Zygote
(d) Testes
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