Science 10

Since the speed of light is 3×108m/s, the distance travelled by the
light in 1 year
= 365×24×60×60×3×108m
= 9.46×1015m
= 9.5×1015m (approximately)
∴1 light year = 9.5×1015m = 9.5 × 1012 km.

Astronomical unit

It is defined as the distance between the earth and the sun. Its value is
1.5×1011m. This unit is suitable for measuring the distance of planets
and satellites in the solar system.
1 AU = 1.5×1011m

Parsec

It is the distance having the value of 3.26 light year.
1 Parsec = 3.26 light year

The solar system

The sun with eight planets, asteroids, satellites, meteorites, comets,
etc form a system called solar system. The sun is the main body of
solar system around which all members revolve. The diameter of
solar system is 10.5 light years.

Asteroid belt

The sun

The sun lies in the middle of the solar system. It keeps all the family
members around it due to huge gravity. Its mass is 740 times greater
than that of the sum of the masses of all planets. It is a medium-
sized star. It seems bigger than other stars because it is nearer from

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the earth. It is about 1.5×1011m away from the earth. The average
density of the sun is 1.5 times more than that of the water. It has been
estimated that the temperature of the surface is 5700 °C and that
of the core is 1.5×107 °C. Its mass is about 1.99×1030kg. Its average
diameter is 1.3924 x106 km. It is 3,32,946 times bigger than the earth.
It takes about 2.5×108 years to complete one revolution around the
galactic centre. This period is called cosmic year.
It consists of three layers. They are photosphere, chromospheres and
corona. Photosphere is the central hottest layer. Chromospheres is
the middle layer of the sun. This layer can be seen during total solar
eclipse only. Corona is the outermost layer. Various types of radiations
such as visible light, infrared, ultraviolet, x-rays, etc are emitted from
the sun. Stream of charged gaseous ions called plasma is continuously
emitted in the form of solar wind. Hydrogen-helium nuclear reaction
is the major source of heat and light radiations of the sun.

Planets

Planets are those members of the solar system which revolve around
the sun in their own elliptical paths called orbits. There are eight
planets in the solar system. The pluto is removed from the list of
planets because it does not have its fixed orbit. Planets do not produce
light. But some planets seem bright due to reflection of the sunlight.
The planets are very small in comparison to the stars. The size,
temperature, distance from the sun, revolution time and rotation time
of the planets differ from planets to planets. The name of the planets
in the order of increasing distance from the sun are as follows:

(i) Mercury (ii) Venus (iii) Earth (iv) Mars

(v) Jupiter (iv) Saturn (vii) Uranus and (viii) Neptune.

These planets can be divided into (i) inner planets and (ii) outer
planets. Those planets which lie inside the belt of asteroids are called
inner planets. Mercury, Venus, Earth and Mars are inner planets.
Those planets which lie outside the belt of asteroids are called outer
planets. Jupiter, Saturn, Uranus and Neptune are the outer planets.

A short description about the planets of the solar system are as follows:

1. Mercury

It is the smallest and closest planet to the sun. It is about

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5.8×107km away from the sun. It is the fastest revolving planet.
It takes about 88 days to complete one revolution
around the sun. It takes about 59 days to
complete one rotation on its axis. Its diameter is
4851 km. Its surface temperature lies between
4270C to -1700C.It has no atmosphere and no
satellite.

2. Venus

It is the hottest and brightest planet of
the solar system. Its surface temperature
can reach upto 4800C. It lies about at 10.7
× 107 km away from the sun. Its size is
approximately equal to the size of the earth.
Its diameter is about 12,035 km. It completes
one rotation around its axis in about 243
days. It completes one revolution around the sun in about 225
days.

It has no moon. It has an atmosphere of carbon dioxide. It is seen
in the eastern sky just before the sunrise and in the western sky
after the sunset. Therefore, it is called morning and evening star.

Fact &Reason

Life is not possible on the Venus though it has water, oxygen and carbon dioxide?
Life is not possible on the Venus though it has water, oxygen and carbon dioxide.
It is because the temperature of the Venus is very high due to the greenhouse
effect caused by the excessive amount of carbon dioxide present in the atmosphere
of the Venus.

3. Earth

It is the third planet from the sun. It is the only planet of solar
system where the life is possible. It has favourable conditions for
the survival of life. Therefore, it is called living planet.

It is about 14.88 × 107 km away from the sun. Its diameter is about
12,672 km. It takes about 24 hours to make one rotation around its
axis. It takes about 365 days to complete one revolution around the
sun. Atmosphere of the earth contains mainly nitrogen, oxygen,
carbon dioxide and water vapour. It has one satellite (moon). Its
surface temperature can reach upto 150C.

4. Mars

It is called red planet. Its soil contains iron oxide due to which it

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is red in colour. It is about 22.56 × 107 km away from the sun. Its
diameter is about 6742 km. It takes about 24
hours and 37 minutes to complete one rotation
around its axis. It takes about 687 days to
make one complete revolution around the
sun. Researches have proved that there was
water present in the past. There is no life. Its
atmosphere contains carbon dioxide, little
water, little nitrogen and little oxygen. It
contains two satellites named Phobos and
Deimos.

5. Jupiter

It is the largest planet of the solar
system. It lies about 76.8 × 107 km
away from the sun. Its diameter is
about 1.13904 x106 km. It takes about 9
hours 55 minutes to make one rotation
around its axis. It takes about 12 years
to complete one revolution around the
sun. It has thin ring around it. It has
a great red spot on the surface. It is
mysterious for scientists. It has 79 satellites. Europa, Ganymede,
Callisto, etc are main satellites of Jupiter. Its surface temperature
is about -1430C in an average.

6. Saturn

It is the second largest
planet of the solar system.
It is about 150×107 km
away from the sun. It takes
about 10 hrs 30 minutes to
complete one rotation on
its axis. It takes 29.5 years
to make one complete revolution around the sun. Its diameter
is about 1,13,600 km. It is surrounded by rings which are about
1000 in number. The density of the Saturn is the least of all. It is
so light that it can float on the water. It has 82 satellites. Titan is
the main satellite. The diameter of Titan is 5140 km.

7. Uranus

It is the second farthest planet from the sun. It was the first planet

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which was discovered by using telescope. It is seen green with
telescope. It is about 288×107 km away from
the sun. Its diameter is about 50442km. It
takes about 17 hours and 14 minutes to
make one rotation on its axis. It takes about
84 years to make one complete revolution
around the sun. It is also surrounded by the
rings. It has 27 satellites. Miranda, Ariel,
Umbriel, Titania, etc are its main satellites.
Its atmosphere contains mainly hydrogen,
helium and methane. Its surface temperature is about -2160C.

8. Neptune

It is the farthest planet from the sun. It
was discovered by Adams and Leverrier
in 1846 AD. It looks green. It is about
448×107km away from the sun. Its diameter
is 48000 km. It takes about 16 hours for one
complete rotation on its axis. It takes about
164 years to make one complete revolution
around the sun. It has 14 satellites. Triton and Nereid are the
main satellites. The diameter of Triton is 2705 km. Its atmosphere
contains mainly hydrogen, helium and methane. It is the coldest
planet.

Table for comparative study of planets

Planets
Avg. distance from the

sun in Km
Least distance from
the earth (×106 km)
Period of revolution

(days or years)
Avg. orbital velocity

(km/s)
Diameter (km)
Period of rotation

(days)t
Surface temperature

(°C)
Gravity (earth=1)

Gases in the
atmosphere
Mass earth = 1
Density (gm/cc)
Density (earth =1)
No. of satellites known

Mercury 57.6×107 891.7 87.97d 47.89 4878 59 d -180 to 427 0.386 - 0.055 5.42 10
Venus 10.72×107 41.4 224.7d 0.97 0
35.63 12104 243 d 482 0.871 CO2, N2, 5.25
Earth 14.88×107 - 365.25d H2O, Ar, CO, 0.815 11
1 5.52
Mars 22.56×107 55.7 686.98d Ne, SO2 0.73 2
0.38 3.99
Jupiter 76.8×107 628.76 12y 29.79 12735 23h 15 N2, O2, CO2, 1 0.25 79
Saturn 144×107 1277.4 29.5y 56m -53 2.53 H2O 1.33 0.13 82
Uranus 288×107 2587 84y 1.07 0.69 0.23 27
Neptune 448×107 4310 164y 24.13 6720 24h 0.91 CO2, N2, Ar, 0.107 1.27 0.30 14
37m 1.14 O2, CO, Ne, 1.64
Kr, Xe, H2O

13.06 140800 9h 55m -150 H2, He, CH4, 317.892
-188 NH3
-210
9.64 113600 10h -225 H2, He, CH4, 95.184
14m NH3, C2H6

6.81 51200 17h H2, He, CH4 14.51
14m

5.43 48000 16h H2, He, CH4, 17.15
C2H2

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Satellites

A satellite is a heavenly body which revolves around a planet. There
are two types of satellites:

a) Natural satellite b) Artificial satellite

Natural satellite

Natural satellites are those heavenly bodies which revolve around the
planets. They do not have their own light. But they shine due to the
reflection of light of the sun.

The moon is the natural satellite of the earth. The diameter of the
moon is about 3456 km. The mean distance between the earth and
the moon is about 3,82,400 km. Moon has less gravity than the earth.
It has no air and water. Moon appears bigger than the stars but it
is very much smaller than the star. Moon appears bigger since it is
nearer from the earth.

It has relative density of 3.3. The time taken by the moon to complete
one revolution around the earth is called sideral month. Its value
is 27 days. Whereas the time period from two consecutive similar
phases of the moon is called synodic month. Its value is 29 days.

Artificial satellite

The satellites which are made by human beings are called artificial
satellites. Artificial satellites are computerized spacecrafts designed
to revolve around the earth in a particular orbit. There are many
artificial satellites sent to the space.

Purposes of launching artificial satellites

i) For the communication of TV, radio, telephone signals, etc.
ii) For forecasting weathers.
iii) To study about the space and different parts of the earth.
iv) To make space station.
v) To carry out various scientific experiments.
vi) To research life in the outer space.

Fact &Reason

Why are artificial satellites launched in space?
Artificial satellites are launched in space for telecommunications, weather
forecasting, military purposes, study of other heavenly bodies , geological
mapping etc.

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Asteroids

In between the orbits of Mars and Jupiter there are small bodies
which move around the sun. These small bodies are called asteroids.
They are also called minor planets or planetoids or baby planets.
They are found in a zone between 1.7 AU and 4 AU from the sun.
This zone is called asteroid belt. The size of asteroids varies from
few kilometers to 800km. Most of the asteroids have irregular shapes
while the bigger asteroids have spherical shape. They are composed
of rocky and metallic substances. Vesta, Hermes, Eros, Ceres, Juno,
etc are some examples of asteroids. Ceres is the biggest asteroid.

Scientists do not have clear concept about the origin of asteroids. It is
believed that the asteroids are the remains of former planets.

Comet

A comet is a frozen mass made up of ice, dust and gases which produces
tail when approaches the sun. They revolve around the sun in very
large elliptical paths.

A comet has mainly three parts. They are nucleus, coma and tail.
The nucleus is the central part which is composed of rock particles
trapped inside frozen mass. When the comet is far away from the
sun, it appears only as a nucleus. But, when it approaches the sun, its
outer frozen mass melts and turns into vapour. The evaporating layer
forms a hazy cloud called coma. The nucleus and coma is collectively
called head of the comet.

Comet's orbit

Earth's orbit

Nucleus Earth Sun

Comet

Comet revolving around the sun
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When the comet approaches the sun, the high energy solar radiations
push the vapour and dust of the comet to form a long tail. The tail
is pointing away from the sun due to solar wind. The solar wind is
formed from charged atomic particles produced from the sun. The
tails of some comets cover the distance of 160 million kilometers. They
can be seen with naked eyes due to long tails when they approach the
sun. Comets do not have their own light. They become visible due to
the reflection of the sunlight. So, they are also called tailed stars.

Fact &Reason

A comet is seen after a long period of time, why?
A comet revolves around the sun in very large elliptical orbit, due to which it
takes many years to make one revolution around the sun. A comet is usually seen
when it comes near the sun. Thus, a comet is seen after a long period of time.

A comet loses ice, dust particles and gases when it approaches the sun.
Thus its size decreases and ultimately converts into a small fragments
like asteroid. Some of the fragments fall in the gravitational field of
the earth while others enter the atmosphere of the earth and get burnt
on rubbing against air.

Halley's comet is the most common comet discovered by an English
astronomer, Edmund Halley. It is seen at the interval of 76 years.
Name of the some comets and their revolution periods are given below:

Name of the comets First appearance Period of revolution
Halley's comet 240 BC
Temple tuttle 1366 76 years
Enke 1786 33 years
Schwasman washman 1927 3.3 years
Shoemaker Levis 1993 15 years
Collided with
Bennet 1969 AD Jupiter in 1994
15 years

Some comets do not appear again in the sky because either they are
completely vaporised or collided with other heavenly bodies.

Meteors and meteorites

Meteor is a rocky or metallic matter which produces light when it
enters the earth's atmosphere during its fall towards the earth. It is
also called falling or shooting star because it looks like a star falling
from one direction to another in the sky. Extremely light and bright
meteor is also called fire ball. When the meteor is in the space it is
called meteoroid. A meteoroid is a solid body consisting of iron or rocks.
When it is pulled by the gravity of the earth, it falls rapidly and rubs

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against atmosphere. The body gets heated due to the heat produced by
friction between the atmosphere and the body. The matter contained
in it converts into gas and vapour and disappears on the way. The
process of falling of large number of meteors is called meteor shower.
When the mass of the meteoroids is large and it does not burn out
completely in the atmosphere, it can reach the earth's surface and is
called meteorite. Such meteorite forms crater on the earth's surface.

In prehistoric era about 50,000 years ago a meteorite had fallen at
Arizona in America. A crater of 1275 meters breadth and 175 meters
depth can still be seen these days. The fragments of the rocks are
found scattered.

Depending upon the composition of materials, meteorites are classified
into three types. They are (i) Stony meteorite (ii) Iron meteorite (iii)
Stony iron meteorite.

Stony meteorite

These meteorites contain more amount of silica and less quantity of
iron and magnesium.

Irony meteorite

These meteorites contain more amount of iron and negligible quantity
of silica. Most of the meteorites that fall on the earth's surface are of
this category.

Stony iron meteorite

These meteorites contain both the silicon and iron in equal amount.

Meteorites found so far range from 100gm to 20,000kg. Especially,
meteors in large number fall near the North and South poles.

Differences between comets and meteors

Comets Meteors

1. The broom shaped shining 1. The piece of rocky substance
objects with bright head which produces light when
made up of ice mass and it enters the atmosphere
elongated tail made up of during its fall towards the
vapour is called comet. earth is called meteor.

2. They produce tail when they 2. They do not produce tail but

approach the sun. produce streak of light.

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Stars
The heavenly bodies which have their own light are called stars. The
heat and light is produced in the stars due to thermonuclear reaction
taking place inside them. Stars contain huge amount of hydrogen and
helium gas. At very high temperature and pressure, hydrogen gas
converts into helium and energy is released. The stars have millions
degrees of temperature at the centre.
There are millions of stars in the universe but we can see about 200
stars with naked eyes. All stars are very big but they seem small
because they are very far from the earth. The sun is a medium-sized
star. The colour of the stars differ. The colour may change from violet
to red in the order of VIBGYOR.
Violet → Indigo → Blue → Green → Yellow → Orange → Red

The temperature of blue star is more than that of green, yellow,
orange and red stars. The temperature of blue star is about 24000°C.
The temperature of yellow star is about 5500°C. The sun is a yellow
star. The red star has minimum temperature. They have temperature
of about 3000°C.

Differences between stars and planets

Stars Planets

1. Stars are the heavenly bodies 1. Planets are the heavenly bodies
which revolve around the which revolve around the sun.
galactic centre.

2. They produce their own light. 2. They do not produce their own light.

3 Generally they are very large 3.Generally, they are smaller in size.
in size.

4. They are millions in numbers. 4. There are only 8 planets in the solar
system.

5.Theyhaveveryhightemperature. 5. They have low temperature.

Constellations

Constellations are the groups of stars which do not change their
positions relative to each other and are arranged in a certain fixed
pattern.

The constellations are small group of stars. The number of stars in a
constellation can be counted. Eighty eight constellations are known
and are given name. Among them, 12 constellations are used as a sign
of zodiac.

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The constellations are given name as the name of animals, gods or
materials. For example, Leo, Pisces, Taurus, Sagittarus, etc. Some
constellations are named on the basis of Greek legends. Andromeda,
Orion, Perseus, etc have been named in such way. Similarly, some
constellations are named as scientific materials. Telescopion, Musca,
Tucana, etc are examples of such constellations.

Uras major ( Saptarishi)

Ursa major is a very common and
easily detectable constellation.
Meaning of ‘ursa’ is woman in Latin.
The shape of this constellation is
like bear. So, it is also called ‘great
bear’. It has seven stars, hence called
Saptarishi. This constellation is
easily visible in April and May in the
northern part of the sky.

Ursa minor ( small dipper)

Ursa minor is also known as little bear.
Number of stars in this constellation are also
seven as in Ursa major, but stars are closer to
each other. Thus, it forms the shape of small
bear. Therefore, it is called little bear. Pole
star is found at the tip of this constellation.
This constellation can be seen clearly in the
northern sky in the month of July and August.

Orion ( kaalpurus)

Orion means hunter in Latin. There are seven
stars in this constellation which are arranged
forming the shape of hunter. There are three
bright stars in the middle which seem like belt
of hunter. Below belt, there are three hanging
stars which are imagined as a weapon. This
constellation is visible in the middle sky in
the month of January and February.

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Superstitions about the Signs of Zodiac
1. There are only 12 Signs of Zodiac but the number of people is more

than 7 billion. Hence, there is no scientific basis for predicting the
future and fortune of people on the basis of their signs of zodiac.

2. There is a practice that people choose their auspicious day, time,
direction based on their sign of zodiac to start a new business,
travel, etc. But, it is not sure that they meet the predicted fortune.

3. Some people are teased or made fun of due to their sign of zodiac.
But there is no scientific basis that people behave according to
their sign of zodiac.

4. People born on the new moon day are regarded as spiritual culprits.
They need spouse born on the same day for getting married to be
safe from unfortunate happenings. However, it does not have any
scientific basis.

5. Getting married by matching planets and the signs of zodiac and
neglecting the other aspects is common in our society. However,
there are a lot of examples that such matched marriages have
turned unsuccessful.

6. Astrologers prepare fortunate finger rings for particular signs of
zodiac. People are supposed to get the desired things and success
if they wear such rings. However, there is no any scientific basis to
support such claims.

Importance of constellation
The constellations have some scientific importance in our society.
People guess time at night by looking at the position of constellations.
They identify the position of stars with the help of constellation.
The constellations also help in the study of planets. The ship sailors
identify their position in the sea and the direction of their destination
by observing the position of constellations in the sky.

Galaxies
There are uncountable number of stars scattered in the space. The
space between the stars is filled by intersteller substances. The stars
remain in groups which contain billions of stars. An extremely large
group of billions of stars, gases and intersteller substance is called
galaxy. A galaxy contains millions of stars. There are about 1011
galaxies in the universe.

The galaxies have the diameter ranging from about one thousand
light years to one million light years. All the stars of a galaxy revolve

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around a central imaginary point called galactic centre or nucleus.
Our solar system is located in Milky Way galaxy.

On the basis of shape, galaxies are classified into three types. They
are spiral, elliptical and irregular galaxy.

Spiral galaxy

Spiral galaxy is seen as spinning spindle with winding arms all
around its centre. The winding arms rotate around the centre. About
70% of the galaxies are spiral. A great amount of dust particles and
gaseous clouds are seen in this galaxy. Andromeda and Milky Way
are spiral galaxies.

Elliptical galaxies

Elliptical galaxies are shaped as a sphere or a flat ellipse. The centre
is bulged. A bright light is emitted from the centre of the galaxy.

Irregular galaxy

Irregular galaxies do not have a regular shape. They have bright
stars at the central part.

According to scientists, galaxies are formed from enormously large
gaseous masses and dust particles. The distance of galaxies can be
estimated by studying infrared rays, radio waves, ultraviolet rays
and x-rays coming from them.

Differences between costellation and galaxy

Constellation Galaxy

1. It is a group of stars 1. It is an extremely large group
which do not change their of billions of stars, gases and
locations. intersteller substances.

2. It has a regular pattern. 2. It has no regular pattern.

3. There are 88 constellations. 3. There are millions of galaxies.

Big bang theory

It is believed that the universe was created in a big explosion called
Big bang. The Big bang theory explains the formation of heavenly
bodies like galaxies, stars, planets etc. According to this theory, all
the matters in the universe were concentrated at the centre which
was 100 million light years wide. This highly dense and extremely hot
mass exploded with Big bang and scattered all over. Thus galaxies,
stars, planets, etc were formed.

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Importance of the sun in the solar system

1. The sun gives heat and light which make life possible on the earth.

2. Every thing around us along with planets and satellites are visible
to us due to the sunlight.

3. Solar battery or cell converts solar energy into electrical energy.
Such solar batteries are used to operate various types of electrical
devices and artificial satellites.

4. The sun makes all members of the solar system move around it.

Learn and Write

1. Mars is called red planet. Why?
Mars contains the soil having the minerals of iron oxide which is

faint red in colour. Thus, the mars is called a red planet.
2. The pluto is not kept in the list of planets. Why?
The pluto does not have its fixed orbit while revolving around

the Sun. Therefore, it is not kept in the list of planets.
3. Comets produce tails when they approach the sun. Why?
Comets are made up of frozen ice, dust particles and gases. When

they approach the sun, the high speed solar wind pushes the
gases and vapour away to form tails. Thus, comets produce tail
when they approach the sun.

Main points to remember

1. The universe is a vast space in which all heavenly bodies including
galaxies, stars, constellations, planets, asteroids, comets, etc are located.

2. Stars are the heavenly bodies which produce their own light and
revolve around the galactic centre.

3. Planets are those members of solar system which revolve around
the sun in their own elliptical paths.

4. There are eight planets in our solar system.
5. The planets which lie inside the belts of asteroids are called inner planets.
6. The planets which lie outside the belts of asteroids are called

outer planets.
7. Asteroids are the small heavenly bodies which lie between the

orbit of the mars and jupiter and move around the sun.
8. A comet is a frozen mass made up of ice, dust and gases which

produces tail when approaches the sun.
9. Meteor is a rocky or metallic matter which produces light when it

enters the earth's atmosphere during its fall towards the earth.
10. Meteorite is the larger meteoroid which does not completely burn

out in the atmosphere and can reach the earth's surface.

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11. Galaxy is an extremely large group of billions of stars, gases and
intersteller substances.

12. Constellations are group of stars which do not change their relative
positions to each other and are arranged in a fixed pattern.

Exercise

A. Very short answer questions (1 mark)

1. What is the universe?

2. Define natural satellite with examples.

3. Name any two terrestrial planets.

4. Name the planet nearest to the earth.

5. Name the coldest planet of the solar system.

6. Name two planets having asteroids between them.

7. What is coma?

8. Write the name of a comet which appears in interval of 76

years from the earth.

9. What is a meteor?

10. What is meant by one light year?

11. Express one light year in terms of meter .

12. What is AU ?

13. Name the largest satellite of Saturn.

14. Name the following:

a. Red planet c. Smallest planet

b. Green planet d. Dwarf planet

15. What is a meteorite ?

16. What is synodic month?

17. What is a satellite? Give examples.

18. What is fireball?

19. How many types of meteorites are there ? Name them.

20. What is galaxy?

21. What is constellation?

22. What is the total number of constellations discovered so far?

B. Short answer questions (2 marks)

1. Write any two reasons that life does not exist on the planet

Mercury.

2. Why are artificial satellites launched in space? Give any four

reasons.

3. Write any two differences between light year and astronomial

unit.

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4. Write any two similarities between the Earth and Venus.
5. Life is not possible in venus though it contains water, oxygen

and carbon dioxide, why?
6. Why is the pluto not considered as a planet of the solar

system ? Give any two reasons.
7. Why does a comet develop a tail when it comes nearer to the

Sun?
8. Write the name, shape, number of major stars in the

constellation given in figure and the season in which it is
visible.

9. Mention any two differences between galaxy and
constellation.

10. A meteor is finished before reaching the earth's surface. Why?
11. A comet loses its tail when it is far from the sun. Why?
12. Mention any two differences between a moon and a star.
13. Mention any two differences between a shooting star and a

star.
14. Differentiate between asteroids and comets in two points.
15. Why does a meteor last only for short time?
16. A comet is seen only after a long period of time, why?
17. A comet is not actually a star. Give two evidences in favor of

this statement.

C. Long answer questions (3 marks)

1. Differentiate between(in three points):

i) Planets and Stars ii) Inner and Outer planets

iii) Meteors and Meteorites iv) Meteors and Comets

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D. Very long answer questions (4 marks)

1. Study the given figure and answer the following questions:

i. Introduce such objects

revolving around the Sun.

ii. Why does the size of tail of

this mass increase when it

comes closer to the Sun?

iii. It cannot be considered as

a star, why? Give any two

evidences.

2. What do you know about Big Bang Theory? Explain in brief.

3. Classify the following into galaxy, comets, asteroids,

satellites, planets and dwarf planets.

Enke, Andromeda, Titan, Shoemaker levy, Pluto, Mars, Juno,

Proxima centaury

Project Work

Observe the sky in the clear night and identify
(i) Stars (ii) Constellation and (iii) Satellites

Glossary

• Galactic : related to galaxy, of the galaxy

• Consecutive : following one after another without interruption
or break

• Spindle : a handheld rod with a notched end through
which strands of natural fibers are drawn, then
twisted into thread and wound around the rod

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Specification Grid (Science)

SEE (Secondary Education Examination) Theory FM: 75

Areas S. Units Total no. of Questions & their marks
No. K U A HA Total

1. Force

2. Pressure

Physics 3. Energy 5×1=5 4×2 = 8 2×3 = 6 1×4 = 4 23
4. Heat

5. Light

6. Electricity and Magnetism

7. Classification of Elements

8. Chemical Reaction

9. Acid, Base and Salt

10. Some Gases 4×1=4 4×2 = 8 2×3 = 6 1×4 = 4 22

Chemistry 11. Metals

12. Carbon and its

Compounds

13. Materials Used in Daily

Life

14. Invertebrates

15. Human Nervous and

Glandular System

16. Blood Circulatory System

in Human Beings

Biology 17. Chromosomes and Sex 5×1=5 4×2 = 8 2×3 = 6 1×4 = 4 23

Determination

18. Reproduction

19. Heredity

20. Environmental Pollution

and Its Management

21. Histroy of the Earth

Geo.&Astr. 22. Atmosphere and climate 1×1=1 1×2=2 X 1×4 = 4 7
change

23. The Universe

Total questions 15 13 6 4 38

Total marks 15 26 18 16 75

Note: K= Knowledege type questions U= Understanding type questions

A= Application type questions HA= Higher ability type questions

Specification Grid(Practical)

Class : X F.M. =25

Areas Sketching /labeling Reporting Material Mini Viva/ Total
characteristics construction project Record
work
5 55 5 25
5

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SEE Exam 2075 (2019)

RE -111 ‘AP” F.M.: 75
P.M.: 30
Class : X Time: 2:15 hrs
Subject: Science

Candidates are required to give answer in their own words as far as practicable.

Attempt all the questions.

Answer all the questions.

Group ‘A’ 1 x 15 = 15

1. Write short answer of the following questions. 1 x 15 = 15

a. What is the value of acceleration due to gravity at the pole of the

earth?

b. What is the alternative source of energy?

c. In which two factors does the heat gain or loss by any object depend

upon?

d. Define converging lens.

e. What is transformer?

f. Write the types of given chemical equation.

(i) C+O2 CO2
(ii) 2KClO3 2KCl+3O2
g. Define neutral salt.

h. Name any two ores of iron.

i. Write general formula of alkene.

j. Write the name of two species of silkworm cultivated in Nepal.

k. Write the name of vein in which pure blood flows.

l. Write any two chromosomal disorders caused by sex chromosome.

m. What is the part of plant called that is used for root in grafting.

n. Mention any two effects of water pollution.

o. In which eras were owl and flowering plants evolved?

Group ‘B’ 13 x 2 = 26

2. Kathmandu lies at high altitude than Biratnagar from sea level.

Where does an object has more weight between two places ? Give

reason.

3. In the context of Nepal, hydro-power should be given more priority

rather than fossil fuel. Why ? Justify with two reasons.

4. What happen if an egg is kept in two breakers containing pure water

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and saturated salt solution ? why ?

5. Mention any two reasons of using nichrome wire in electric heater.

6. Write any two characteristics of modern periodic table.

7. Write the balanced chemical reaction between aluminum metal and

dilute hydrochloric acid. Mention the type of reaction with reason.

8. Write a structural formula of glycerol and write any one use of ethyl

alcohol.

9. Write any two functions of organic fertilizer.

10. Write two differences between axon and dendrites.

11. Write two differences between systemic and pulmonary blood

circulation. (22,x) (22,x) (22,x)
12. Which process is represented by given chart ? (22,y) (44,xx) (44,xx)
(44,xy) (44,xy)
According to that process write down differences
between (44, xx) and (44, xy).

13. Write any two differences between drone bee and worker bee.

14. Why is meteor generally finished before reaching the earth surface.

Group ‘C’ 6 x 3 = 18
250N

15. What is the condition for an object to sink in water ? The A1 50cm2 0.2m2
cross- sectional area of piston A1 and A2 is 50cm2 and 0.2m2 A2

respectively. How much load can lift in piston A2 if 250N

force is applied on piston A1.

16. Prove that heat loss or gain by an object is equal to the product of

mass of object, specific heat capacity and change in temperature.

17. In the given figure, red litmus paper is inserted in solution and

colour remains unchanged then what may be contained in vessel

among acid, base and salt solution? How can it be further tasted

to confirm it ?

18. Why is glass called fourth state of matter ? Write any two uses of

water glass and lead crystal glass.

19. Draw neat and clean diagram of reproductive part of plant and label

its four major parts.

20. What will you suggest to your neighbors so that it can help to reduce

soil pollution ? Write any six suggestions. 

Group ‘D’ 4 x 4 = 16

21. Draw a ray diagram of an image formed when an object is placed at

a distance of 10cm from a convex lens having focal length 20cm. Write

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any two nature of image. Calculate the power of lens. xfO8f]S« nfl/] s cDn
22. Study the given diagram and answer the following questions.

i) Which gas is collected in gas jar?

ii) Why is the gas jar kept erect?

iii) What happens when gas is reacted with potassium rg' 9ª' u\ f

hydroxide ? Write the balanced chemical equation.

23. Draw a chart to show the first generation and second generation

resulted due to the fusion of games of long - winged housefly (HH)

and short - winged housefly (hh). Which generation shows the law of

purity of gametes ? justify it.

24. Write the name of main chemical which destroys ozone layer. How

ozone layer is depleted by that chemical ? Describe with chemical

equation.

417 Times' Crucial Science Book - 10

418Times' Crucial Science Book - 10