Class 10 Science Solutions Nepal

iii. It maintains water cycle on the earth.
iv. Solar energy is used by the plant for photosynthesis.
v. Solar energy can easily be converted into electricity by using solar battery, which

can be used for various purposes like cooking, heating, lightening, etc.

MEMORY TIPS
Chromosphere of the sun can only be seen during the total solar eclipse.

Planets

These are the heavenly bodies, which revolve around the sun in their own elliptical
orbit. There are 8 planets in our solar system. They are Mercury, Venus, Earth, Mars,
Jupiter, Saturn, Uranus and Neptune.

These planets are again divided as outer and inner planets. The planets which lie inside
the asteroid belt, i.e. Mercury, Venus, Earth and Mars are inner planets or terrestrial
planets and those planets which lie outside the asteroid belt are called outer planets.
Jupiter, Saturn, Uranus and Neptune are the outer planets or Jovian planets.

Inner planets have thin rocky crust and the core of molten metals. The outer planets are
made up of gases having a ring-like structure around them. Therefore, outer planets
are also called gas giants.

MEMORY TIPS
Planet means ‘wanderer’ in Greek language and this name is given as the planets revolve
around the sun.

A short description about each of the eight planets is given below:

(i) Mercury (Budha)
It is the nearest, smallest and the fastest revolving planet. Its
rotation period is 59 days and revolution period is 88 days.
It does not have any satellite and atmosphere. The days are
very hot and nights are extremely cold on it. Its diameter is
about 4880 km. (0.4AU)

(ii) Venus (Sukra)
It is the brightest and hottest planet. It is also known as the
morning or the evening star as it is seen in the sky before sunrise
and just after sunset. Its mean distance from the sun is 1.08 ×
108 km (0.7AU) and has a diameter of about 12104 km. It does
not have any moon. It is the closest planet from the earth. It is
also called the sister planet of the earth.

New Creative Science, Class 10 | 347

MEMORY TIPS
In Venus, the sun rises from the west and sets in the east dut to the extreme inclination of
its axis which is beyond 180°.

(iii) Earth (Prithvi)
It is also called the green planet or the blue planet. It is the only
planet in the solar system which has the suitable condition
for the survival of living beings. Its distance from the sun
is 1.5 × 108 km (1 AU). Its rotation period is 24 days and
revolution period is 365 days. Its diameter is 12,756 km. It
has only one satellite i.e. the moon.

(iv) Mars (Mangal)
It is the red planet. Its distance from the sun is about 2.26 × 108
km, (1.6 AU) and its diameter is about 6720 km. Its rotation
period is 24 hours 37 minutes and it takes 687 days for the
completion of one revolution. Phobos and Diemos are the two
satellites of Mars.

MEMORY TIPS
• Mars is seen red because its surface consists of limonite (iron oxide).
• Nix Olympia (Olympus) is an extinct volcano in Mars and is 3 times the height of Mt.

Everest.

(v) Jupiter (Brihaspati)
It is the largest planet. The clouds on Jupiter form bright and
dark grey hands on the surface. Its distance from the sun is
about 7.78 ×108 km (5.2 AU) and its diameter is about 140800
km. Its rotation period is 10 hours and revolution period is 12
years. It has a red spot on its surface. It has 63 satellites.

(vi) Saturn (Sani)
It is the second largest planet having prominent rings made
for up of rock particles and snow. It is approx 16.294 × 108
km (10 AU) away from the sun. Its diameter is about 120585
km. Its rotation period is 10 hours 14 minutes and revolution
period is 29.5 years. It consists of about 60 satellites. The
biggest satellite of Saturn is ‘Titan’.

348 | The Earth in the Universe

MEMORY TIPS
The density of Saturn is so less (0.6 g/cm3) that it can float on water.

(vii) Uranus (Arun)

It is made up of fluids. It is not solid but is made up of the small
crystals of methane gas. Its mean distance from the sun is 2.87
× 109 km (19.6 AU). Its diameter is about 51200 km. Its rotation
period is 17 hours and 14 minutes, and revolution period is 84
years. It consists of 27 satellites.

(viii) Neptune (Barun)

This is the farthest and coldest planet from the sun. Its mean
distance from the sun is about 4.48 × 109 km, (30 AU) its
diameter is about 48,000 km. It is made up of hydrogen, helium
and methane. It consists of 13 satellites among which Triton is
the biggest one.

ACTIVITY

Draw the solar system in a chart paper and colour them.

QUESTIONS

# Why is Venus called the hottest and brightest planet?
# Which planet is called the red planet. Why?

Differences between planets and stars

Planets Stars

1. Those heavenly bodies which 1. Those heavenly bodies which do not

revolve round the sun are called revolve round the sun are called stars.

planets. 2. They are luminous objects.

2. They are non luminous objects. 3. They twinkle at night.

3. They give continuous light at night

due to the reflection of the sun light. 4. They have comparatively a very high
temperature.
4. They have comparatively a very low
temperature.
5. They are big in size.
5. They are small in size.

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Satellites

Satellites are the heavenly bodies, which revolve around the planets in their own orbit.
Satellites are of two types.

(i) Natural satellites (ii) Artificial satellites

(i) Natural satellites

Satellites which are naturally revolve round a planet are called natural satellites.
Among all the eight planets in the solar system, only Mercury and Venus do not have
satellites and the remaining other planets have one to many satellites. There are 152
natural satellites found till now.

Moon

It is the only one natural satellite of the earth and is the brightest

body in the sky and nearest celestial object to the earth. Some

facts about the moon are given below:

i. Distance from the earth – 3,85,000 km

ii. Surface area of the moon– 37,940,000 km2.

iii. Diameter = 3476 km

iv. Temperature range = (–125°C to 130°C)

v. Gravity = 1 th of the earth’s gravity
6
vi. Time taken by moon to

Complete one revolution around the earth (sidereal month) = 27 1 days
3
1
vii. Time period between one full moon to another (synodic month) = 29 2 days

MEMORY TIPS
The moon has about 30 plains, 30,000 craters and mountains on its surface.

ii) Artificial satellites

The satellites which are man-made and allowed to revolve certain planets from a fixed
distance for various purposes are called artificial satellites.

Purposes of launching artificial satellites

(1) To study the weather patterns of the
earth.

(2) They are launched to communicate
signals of the radio, television, telephone,
etc.

(3) To know the exact position of navigators
in air or in the oceans.

350 | The Earth in the Universe

(4) For scientific research, study of cosmic rays and solar radiations.
(5) For observing the military troops movement and detecting the test of nuclear

weapons in the space.
E.g. of artificial satellites: INSAT, IRS, Kalpana-I, Sputunik-I, EDUSAT, etc.

ASTEROIDS

The celestial bodies which revolve around the sun in the space between the orbit of
Mars and Jupiter are called asteroids or small planets or baby planets. The diameter of the
largest asteroid (Ceres) is about 800 km and other asteroids having a diameter from
1.6 km to 3.2 km are also found. Example: Juno, Vesta, Pallas, Eros etc.

The Asteroid belt

COMETS

Comets are also the members of our
solar system. They revolve around the
sun in highly elliptical orbits. Their
period of revolution round the sun is
usually very long.
A comet appears generally as a bright
head with a long tail. The length of the
tail grows in size as it approaches the
sun. The tail of the comet is always
directed away from the sun. The head
is made up of ice-mass. The head is also known as coma which contains a central part
called the nucleus.
Many comets are known to appear periodically. One such comet is Halley’s comet,
which appears after nearly 76 years. It was seen in 1986 AD.

New Creative Science, Class 10 | 351

S.N. Name of Comets First Observed Revolution (years)

1 Halley’s comet 240 BC 76
33
2 Temple- tutle 1366 AD 33
15
3 Enke 1786 AD 16
78
4 Schwasman- Washman 1927 AD

5 Bennet 1969 AD

6 Shoemaker Levi 1992 AD

When a comet is away from the sun, its tail is not formed as the ice-mass is not
evaporated. Some comets never return as they may collide with other heavenly bodies
and may get destroyed, e.g. Shoemaker Levi collided with Jupiter in 1994 AD.

METEORIDES, METEORS AND METEORITES

At night, when the sky is clear and the moon is not there, we may sometimes see bright
streaks of light in the sky for a short time. These are commonly known as shooting stars
(falling stars), though they are not stars. They are called meteors.

A meteor is usually a small object that occasionally enters the earth’s atmosphere with a very
high speed. The friction due to the atmosphere heats it up. It glows and evaporates
quickly. That’s why the bright streak lasts only for a very short time.

Some meteors are large. So, they can reach the earth before they evaporate completely.
Such body which reaches the earth is called a meteorite. Meteorites help scientists to
investigate the nature of the materials from which the solar system was formed.

MEMORY TIPS

When the earth crosses the tail of a comet, showers of meteors are seen. These are
known as meteor showers. Some meteor showers occur at regular interval of each year.

Meteorites are of three types:

(i) Stony – They have silicon more than iron and magnesium.
(ii) Iron – They have more iron and less silicon.
(iii) Stony iron meteorites – They have equal an amount of silicon and iron.

GALAXY

Our universe consists of billions and billions of stars among, which the sun is just a
middle-sized star. That means there are also other stars, which are bigger than the sun.

The group of billions of stars, star clusters, nebulae, dust and gas all held together by the
gravity is called galaxy. There are about 1012 galaxies in the universe, e.g. Milky Way
galaxy, Andromeda galaxy etc. All the stars of galaxy revolve around the hypothetical
centre known as galactic center or nucleus.

352 | The Earth in the Universe

The diameter of galaxies varies from one thousand light year to hundred thousand
light years. Scientists measure the distance between galaxies on the basis of the study
of rays like IR, x-rays, Y-rays, uv- rays emitted by the stars.

TYPES OF GALAXIES

Spiral galaxy

These galaxies have spiral shapes. In their centre, there are spiral arms. These galaxies have
enough gases and dust particles. These galaxies are brighter than other galaxies. For example,
Milky way galaxy, Andormeda galaxy, etc.

Elliptical galaxy

They have an elliptical shape. They have a large amount of interstellar matter. These galaxies
have comparatively old stars. From the centre of these stars, bright light comes out. For
example, fornax and sculptor

Irregular galaxy

These galaxies have irregular shapes. They are less bright than spiral galaxies. For example,
NGC 6822 and IC 1613

Milky Way Galaxy

Our solar system lies in one of the corners of the Milky Way galaxy. In this galaxy, there are
about 1011 stars. The structure of the Milky Way galaxy is like a convex disc. Its central part is
thicker and its edge is thinner. In the gaps between the stars, there is a cloud of dust. The mass
of the Milky Way galaxy is about 1.33*1011 times as big as the solar mass.

BIG-BANG THEORY

This law gives the idea about the formation of galaxies and the universe. According
to this theory, the entire mass of the universe was accumulated as a fireball, which
exploded about 13 billions years ago, and the constituents of galaxies and the universe
were formed. The universe is still expanding i.e. galaxies of the universe are moving
away from each other.

CONSTELLATIONS

A group of few stars which may change their
position but do not change their shapes in the
sky are called constellations. There are about 88
constellations known to us, among which 12
are used as the sign of zodiac.

Constellations were devised by ancient
people to be able to recognize stars in the sky.
The shapes of constellations resemble objects
familiar to those people.

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E.g.: Great Bear (Ursamajor)

Ursa minor Cassiopeia Leo major Orion

Aries Libra Sagittarius Scorpio
Cancer Aquarius Scorpio Gemini
Scorpio Virgo
Pisces Leo

Cassiopeia Ursa Minor Cepheus Ursa Major

Ursa Major

It is also known as the great bear or Saptarishi. In Latin language,
Ursa means a woman. The shape of the Ursa major is like a bear.
According to the Hindu ethic, it has seven stars, so it is also called
Saptarishi. In the months of Baishak and Jesth, Ursa major can be
seen in the northern sky. It is the third largest constellation in the sky.

Ursa Minor

It is also known as little bear or Laghu Saptarishi. It also
has seven bright stars. The shape of the Ursa Minor is like
Ursa Major. At the end of Ursa Minor, there is Polar star
(Dhurba tara). In the months of Ashad and Sharwan, Ursa
Minor can be seen in the northern sky.

Orion

In this constellation, there are seven stars. It looks like a hunter. It can
be seen in the sky during the months Poush and Magh.

ZODIACS AND THE SUPERSTITIONS RELATED TO THEM

As the earth revolves around the sun, the sun traces a certain path through the sky
known as the ecliptic. This path has 13 groups of stars, among which 12 are considered
by astrology as zodiac constellations. Zodiacs are 12 out of 13 groups of constellations
that have astrological significance. These zodiac constellations are:

a) Aries b) Taurus

c) Gemini d) Cancer

e) Leo f) Virgo

354 | The Earth in the Universe

g) Libra h) Scorpius (Scorpio in astrology)
i) Sagittarius j) Capricornus (Carpricorn in astrology)
k) Aquarius l) Pisces

The 13th zodiac constellation which is not considered by astrologers as a zodiac is
Ophiuchus. Astrology claims to tell the horoscopes of people by studying these 12
zodiac constellations. When a child is born, it is given a zodiac sign and a name on the
basis of it. The belief is that the name and the zodiac sign determine the omen of that
person. Marriages also seem to be fixed with brides and trains that have favourable
matches of their zodiacs. In fact, this practice of astronomy is about 2000 years older,
which was based on the false data of the position of stars. The sky and the position of
the stars seen from the earth and that it changes slightly every year. Even if astrology
is based on the actual positions of stars, its claims have no scientific evidence and
logical values. Much of its beliefs are superstitious.

Some superstitions related to the horoscopes or zodiacs

i) People born on the same day may not have the same fate: The zodiacs for
horoscopes are 12 in number but the total number of people in the world
is billions. All these people get their horoscope signs according to their
date of birth. Astrologers predict that the people born at the same time
throughout the world have the same fate. This is not observed, empirical
and scientific.

b) People born in any particular day of the year are not less ill-fated than
the rest. Our society considers people born on the day of the New moon
(Aunsi) as ill-fated New-mooners (Aunsiya). The society forces these people

New Creative Science, Class 10 | 355

to marry people born on the same day, and believes that if it is not done,
their marriage life and purpose will expire. This is completely unscientific.
Marriages work with mutual understanding, love and respect for each
other and not just because you were or not born on that particular day.

c) People born on the 19th lunar mansion (Moola Nakshatra) are said to have
ill-omen and are humiliated and demeaned by the society. The lunar
mansions are just the positions, in which the moon moves along. There is
no scientific evidence that they have an impact on human life.

d) People judge the behaviour of other people and call names on the basis of
their zodiac signs. In reality, the relation of zodiac signs with the behaviour
of people is unscientific.

e) People prefer their zodiac signs to predict their omen during important
events like owing a house or a motorbike. Life is full of ups and downs.
Buying a house or a bike of a particular colour on a particular day does not
guarantee the safety of itself and the owner.

f) It is observed that people use the prediction of their zodiac signs, names
and the direction as the basis of their travel date, journey and other
important events. This activity is not based on any proved scientific and
experiential evidence. Hence, it should be absolutely rejected on the basis
of logical grounds.

g) People are seen wearing rings that they believe would bring good omen
to their life or prevent ill fate. This is based on the predictions of their
respective zodiac signs. Some of them have all the fingers of their hands
with rings for various astrological purposes. This is truly a belief that is
not supported by scientific evidence and empirical data.

h) People often confuse astrology with astronomy. Astronomy is a branch of
science which is based on scientific truths and empirical ideas while astrology
is based on belief systems that have no scientific evidence and proof.

Since, the significance of zodiac constellations in our life has no scientific proof and
is not verified by empirical data we should not spend our time and money on such
things. We should not believe in something that does not have scientific evidence.
If horoscopes could work, people having the same zodiac sign would all behave in
a similar manner and have ups and downs in the life in the similar predicted way.
Therefore, instead of going after these kinds of practices, one should illuminate
himself or herself with scientific understanding and thoughts. But, if one has an inner
psychological obligation to believe, it is true that he or she may receive peace even
through such false practices. These are of course for people who do not understand or
want to understand science or logical reasoning.

356 | The Earth in the Universe

ACTIVITY

Observe the constellation (Ursa major) for few hours. Do you find any change in its shape? Do you
find any change in its position?

Differences between galaxy and constellation.

S.N. Galaxy S.N. Constellations

1. It is a group of billions of stars. 1. It is a group of few stars.

2. It has no regular pattern. 2. It has a regular pattern i.e. fixed shape.

3. There are about 1012 galaxies. 3. There are 88 constellations known so far.

The heavenly bodies having their own heat and light and that revolve around the galactic
centre of their respective galaxies are called stars. There are billions and billions of stars
in the universe. They can produce their own energy due to the thermonuclear fusion
reaction in which hydrogen continuously changes into helium.

Colour of stars and their age

The colour of stars keep on changing in the order of VIBGYOR

Violet → Indigo → Blue → Green → Yellow → Orange → Red

Blue stars are the youngest stars and have the surface temperature of about 24000°C.
Similarly, yellow or orange stars are the middle-aged stars having the temperature of
about 5500°C and red stars are the oldest stars having the lower temperature of all.

Evolution of star

The evolution of stars can be explained in various stages from birth till death.

(1) The Nebula in space slowly increases in size as its gravity attracts more and
more interstellar materials to it. Finally, these materials are compressed so that
it has a dense hot core and it is called the protostar. This is the birth of the star.

(2) The process of the contraction of the interstellar material continues and when
the temperature of the core reaches 8 × 106°C, then the nuclear reaction starts in
it. Now, it is a star. It takes about 105 years to form a protostar and the protostar
again takes 105 years to form a star.

A star has a delicate equilibrium in which gravity pulling inward and the
pressure of radiation heat outward is balance. This makes the size of the star
constant.

(3) After a certain time, when the maximum amount of hydrogen is converted into
helium, the star will have helium core. This star then cannot undergo fusion
reaction. As a result due to more gravitational pull, the helium core contracts and
the remaining hydrogen expands. Thus, the size of the star increases and its surface

New Creative Science, Class 10 | 357

temperature falls. The star appears red and this condition is called Red giant.

If the mass of a star is high, then it forms super red giant.

Our sun will become a red giant in 5 billion years.
(4) After the formation of the red giant, the star will either become white dwarf or

become supernova according to the mass.
If the mass of a star is the same as that of the sun or less than it, the outer layer
escapes and the inner core still appears white called white dwarf. The white dwarf
will eventually change into red and then black dwarf when cooled.
If the mass of a star is more than that of the sun, the inner core pulls the outer
layer of H2 and the helium core undergoes a nuclear reaction. Finally, the star
explodes and such a star is called a supernova.
5. If the remnant of a supernova explosion is more than 1.4 times but less than 3
times of the sun, then it forms a neutron star and finally to a pulsar.
A rapidly spinning neutron star surrounded by an extremely powerful magnetic
spin is called a pulsar.
The star having only the neutron is called a neutron star. They have of diameter
of only 20-30 km.
6. Finally, the stars having mass more than 3 times that of the sun, it collapses and
forms a black hole. It is due to the continuous collapsing of the solar mass in the
area of about 3-km across.

A black hole is the remnant of a star condensed in such a way and that its gravitational pull
is so enormous that even light cannot get escaped through it. So, it is invisible in the space.

The black holes are discovered by studying the X-rays emitted by them. It is believed
that galactic centres are the black holes.

Diagram showing various stages of stars

Protostar

Star

Red-giant star

W hite dwarf Supernova

Red dwarf Neutron stars Blac k hole

Blac k dwarf Pulsars
358 | The Earth in the Universe

MODEL QUESTIONS ANSWER

1. Venus is the hottest and brightest planet. Why?
Ü Venus has the atmosphere of CO2 gas, which is a greenhouse gas. So, it traps the

solar radiation and becomes the hottest and brightest planet.

2. Mars is called a red planet. Why?
Ü Mars is called the red planet as it appears red due to the presence of iron oxide

(limonite) on its surface.

3. Earth is called the blue/green planet. Why?
Ü Earth is called the blue/green planet as it is seen so due to the reflection of light

from the water bodies on its surface.

4. How life is possible on the earth?
Ü Life is possible on the earth because the earth has water, suitable temperature,

pressure, atmosphere having O2 as the abundant gas, etc.

5. Some comets never return. Why?
Ü Some comets never return because they may have collided with other bodies,

e.g.: Shoemaker Levi had collided with Jupiter in 1994 AD.

6. A comet is also known as a tailed star. Why?
Ü A comet is also known as a tailed star because it forms a long tail like structure as

it approaches the sun due to the evaporation of frozen materials in the opposite
direction of the sun.

7. What will happen to our sun after 5 billion years?
Ü After 5 billion years, almost all the hydrogen in it will convert into helium thereby

forming the red giant. After the formation of the red giant, the sun changes into
a white dwarf, which finally gets cooled to from a black dwarf.

8. Will our sun change into a Black hole?
Ü No, because its mass is less so as to form a black hole. The mass of a star must be

more than 3 times the mass of our sun to form a black hole.

9. Asteroids are called minor planets. Why?
Ü Asteroids are called minor planets because they revolve around the sun as same

as that of planets. But, they do not have a fixed orbit and are smaller than the
major planets. They revolve around the sun in the region between the orbits of
Mars and Jupiter.

10. Black hole is invisible. Why?
Ü The gravitational force of the black hole is so enormous that even the light

entering it cannot escape through it. So, it is invisible.

New Creative Science, Class 10 | 359

SUMMARY
 The aggregate of all the existing things is called the universe.
 The units used for measuring the distance in the universe are called astronomical units (AU).

E.g. parsec and light year.
 The whole group of planets, asteroids, satellites, comets, meteors and meteorites, which

revolve around the sun is called the solar system.
 The moon is the natural satellite of the earth.
 Asteroids are the heavenly bodies of the solar system, which revolve around the sun in the

space between the orbits of Mars and Jupiter.
 Comets are also known as tailed stars.
 Meteors burn up in the atmosphere but meteorites reach the earth’s surface.
 Stars also born, become mature and die.
 The colour of stars can determine their age.
 Protostar is the newly formed star.
 Red giant is the stage of the death of a star.
 Our sun will convert into a black dwarf.
 The stars having mass 3 times more than that of the sun they become a black hole finally.
 Black hole is the remnant of a star which has an enormous gravitational pull.
 The exploding star is called the supernova.

EXERCISE

1. What is the universe?

2. What are the units used to measure the distances in the universe?

3. Define the solar system. In which galaxy does our solar system lie?

4. Write short notes on:

(a) The sun

(b) The biggest planet

(c) Earth

(d) Saturn

5. What do you mean by a satellite. Name some artificial satellites. What are the
uses of artificial satellites?

6. Why are comets known as tailed stars? Some comets never return. Why?

7. Define asteroids. How are they differ from other major planets?

8. Differentiate between:

(a) meteor and meteorite

(b) galaxy and constellation

360 | The Earth in the Universe

(c) planet and stars

(d) protastar and red giant

9. How does the colour of stars determines their age?

10. Name:

(a) the biggest planet

(b) the brightest planet

(c) the hottest planet

(d) the red planet

(e) the planet with rings

11. What is a supernova? How is it formed?

12. Write in a short about the evolution of stars.

13. What is a red giant and a super red giant? Why does its size reach the maximum
level?

14. Give reasons.

(a) A black hole is invisible.

(b) The tail of the comet disappears as the comet goes far away from the sun.

(c) Will our sun be converted, to black hole?

15. Name any two,

(a) Natural satellite

(b) Artificial satellite

(c) Asteroid

(d) Comet

(e) Galaxy

(f) Dwarf planet

(g) Satellite

16. What are pulsar stars and neutron stars?

17. What is a black hole and how is it formed?

18. What is the importance of the sun?

A

B GLOSSARY
C

Celestial bodies : heavenly bodies
Galactic centre : centre of galaxy
Galaxy : group of billions of stars which revolve around the galactic centre
Streak : a long thin mark of line

Constellation : group of few stars having fixed shape



New Creative Science, Class 10 | 361

Specification Grid

Subject : Science Full Marks: 75
Class : Ten Time: 2:15 Hours

AREA Topics K U A H.A Total
Marks

1 F orce

2 P ressure

Physics 3 Energy 5×1 4×2 2×3 1×4 23
4 H eat

5 L ight

6 Electricity and magnetism

7 Classification of elements

8 C hemical reaction

Chemistry 9 Acid, base and salt

1 0 S ome gases 4×1 4×2 2×3 1×4 22

1 1 M etals

1 2 H ydrocarbons and their compounds

1 3 Materials used in daily life

1 4 Inv ertebrates

1 5 H uman nerv ous and glandular system

1 6 Blood circulatory system in human body

Biology 1 7 C hromosomes and sex determination 5×1 4×2 2×3 1×4 23
1 8 A) Asex ual and sex ual reproduction

1 8 (B) Artificial vegetative propagation in plants

1 9 H eredity

2 0 Env ironmental pollution and management

Geo and 2 1 History of the earth
Astro
2 2 C limate change and atmosphere 1×1 1×2 …….. 1×4 7

2 3 The univ erse

Total questions 15 13 6 4 38

Total Marks 15 26 18 16 75

Note : Questions will be asked from each unit.
K = Knowledge
U = Understanding
A = Application
H.A = Higher ability

362 | New Creative Science, Class 10

A sample set of model question

Group 'A' [15 × 1 = 15]
1. Define acceleration due to gravity.
2. State law of floatation and name any one instrument based on it.
3. What are alternative sources of energy? Write an example.
4. What is power of lens? Write down its SI unit.
5. What is meant by 1kWh?

6. State Mendeleev’s Periodic law.
7. Define acid-base reaction.
8. Write down any two inorganic acids with their molecular formula.
9. Which metals can be extracted from argentite and hematite ores?
10. What is cocoon?
11. Define gene?
12. What are endocrine glands? Write the name of an exocrine gland.
13. Write down the name of any two organisms which reproduce by means of budding.
14. Define dominance and recessive characters.
15. Write down any two gases which are responsible for ozone layer depletion.

Group 'B' 13 × 2 = 26

16. Write down any two causes that bring energy crisis.

17. If the weight of a stone in three different media air, water and salt solution are given in

the table, study the given table and answer the following questions.

Media Weight

A 15 N

B 18 N

C 16 N

a. Which one is water and which one is salt solution?

b. Find the mass of water displaced by the stone.

18. A student cannot see the black board from the last bench of the class. What type of

defect of vision is present in his eyes? Write down the type of lens which can be used to

correct this defect.

19. Name the device which is shown in the given figure. Write down any

three methods to increase its power.

20. Show the sub-shell electronic configuration of chlorine and calcium.
21. Write down any two differences between saturated and unsaturated hydrocarbons.
22. Write down any two causes and two control measures of chemical pollution.
23. All alkalis are bases but all bases are not alkalis. Why?
24. Write two differences between cerebrum and cerebellum.
25. Identify the given figures and name them.

26. Write down any two characteristics of the silk fibres. ab cd

New Creative Science, Class 10 | 363

27. What are the causes of high blood pressure? Write down any two points.

28. We see comet after very long interval of time. Why?

Group 'C' 6 × 3 = 18
29. The mass of the earth is 6 × 1024 kg and its radius is 6400 km. what will be the

acceleration due to gravity on the earth? Calculate the weight of a person of mass 80 kg

on the earth’s surface?

30. On the basis of specific heat capacities of the three different substances, answer the

Following questions:

Substance) Specific heat capacity)

A 140 J/kg°C

B 800 J/kg°C

C 4200 J/kg°C

a. What do you mean by specific heat capacity of A is 140 J/kg°C?
b. Which one of the above substances will gain more temperature if they are

supplied with equal amount of heat? Also write correct reason.
c. If equal mass of all three substances are heated up to 100°C, and allowed to

cool down, then which one will cool fast and why?
31. Write down any three uses of ammonia gas.
32. Organic fertilizers are better than chemical fertilizers. Justify your answer with any

three points.
33. Which endocrine gland is called the master gland? Write down any two hormones

secreted by this gland. Write down any two importance of the hormones secreted by
this gland.
34. Write down any two causes, two effects and two control measures of the soil pollution.

Group ‘D’ 4 × 4 = 16

35. Observe the given diagram and answer the following questions.

i. What type of defect of vision of eye is given in the diagram?

ii. Write down any causes of this defect.

iii. What type of lens can be used to correct this defect?

iv. Draw the corrected diagram after using suitable lens.

36. Observe the given diagram and answer the following questions.

i. Which gas is going to be prepared according to the given diagram?

ii. Name the chemicals which are required to prepare this gas.

iii. Why is this gas collected by upward displacement of air?

iv. Write down any two uses of this gas.

37. What is law of dominance? Show the cross with phenotypic and genotypic ratio when tall

pea plant is crossed with dwarf pea plant.

38. Complete the table with the correct answer.

Era Duration Animals and plants that were evolved in these eras

Mesozoic era

Cenozoic era

364 | New Creative Science, Class 10