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.

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.

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.

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)

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

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?...

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.

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

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

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.

_______________________________________________________

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.

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

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

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.

Q5: The property of plane mirror to make 'right appear as left' and vice versa, is called:

CBSE Class 8 Science - CH 14 - Chemical Effects of Electric Current (MCQs)

Chemical Effects of Electric Current

MCQs

Q1: 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

CBSE Class 6-12 - Science - Fathers in Biology

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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

CBSE Class 8 - Science - Ch 13 - Sound (MCQs)

Sound

MCQs

Q1: 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.

CBSE Class 8 - Science - Ch 6 - Combustion & Flame (MCQs)

Combustion & Flame

Combustion & Flame
credits:openclipart

(MCQs)

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?

CBSE Class 8 - Science - CH10 - Reaching Age of Adolescence (MCQs)

Reaching Age of Adolescence 

Adolescents

MCQs

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

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

CBSE Class 8 - Science - CH12 - Friction (MCQs)

Friction

MCQs

Q1:  Which friction of the following is the highest?

(a) Sliding friction.
(b) Rolling friction
(c) Static friction
(d) None of these

Q2:  Friction is a ______.

(a) type of contact force.
(b) type of non-contact force.
(c) type of pressure.
(d) form of heat.



Q3: An object is at rest on a floor, a force is applied to move that object. Which friction force will come into an action at this moment?

(a) Sliding Friction
(b) Static Friction
(c) Rolling Friction
(d) Fluid Friction

CBSE Class 8 - Science - Ch5 - Coal and Petroleum (MCQs)

Coal and Petroleum

MCQs

Q1: The resources present unlimited quantity in nature and can be used over and over again are known as _________

(a) Gases
(b) Fuels
(c) Renewable Resources
(d) Energy


Q2: LPG stands for?

(a) Liquefied Petroleum Gas
(b) Liquid Petroleum Gas
(c) Liquefied Petro Gas
(d) Liquefied Petrochemical Gas


Q3: Petroleum and coal are ...

(a) Gases
(b) Metals
(c) Energy
(d) Fossil fuels


Q4: Which of the following is not a petroleum product?

(a) Gas
(b) Petrol
(c) Diesel
(d) Coal