Term 3 · Class 7 Science · Chapter 2

Samacheer Class 7 Science - Universal and Space

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Chapter-wise textbook exercise answers for Universal and Space with validation-aware solutions.

Answers marked verified were checked during generation against the chapter context and source question text.
Sections in this chapter
I. Choose the correct answers: 5II. Fill in the blanks 1III. True or False – If False give the correct answer 5IV. Match the following: 1V. Analogy: 2VI. Very short answer: 7VII. Short Answer Questions: 3VIII. Answer in Detail: 2IX. HOT Question: 1
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1I. Choose the correct answers:5 questions
Q.1The Moon takes ________ days to complete one revolution around the Earth.v
  1. A. 25
  2. B. 26
  3. C. 27
  4. D. 28
Solution

(c) 27

Answer:

(c) 27

Q.2If the Moon is appeaing in the sky today near the star Karthikai, the position of the Moon after 27 days is near the Starv
  1. A. Bharani
  2. B. Karthikai
  3. C. Rohini
  4. D. Asvini
Solution

(d) Asvini
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Answer:

(d) Asvini
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Q.3Telescope was invented byv
  1. A. Han Lippershey
  2. B. Galilio
  3. C. Nicolus Coppernicus
  4. D. Ptolomy
Solution

(a) Han Lippershey

Answer:

(a) Han Lippershey

Q.4The galaxy containing young and hot stars isv
  1. A. elliptical galaxy
  2. B. irregular galaxy
  3. C. cluster
  4. D. spiral galaxy
Solution

(d) spiral galaxy

Answer:

(d) spiral galaxy

Q.5With the launch of this satellite, ISRO became capable of launching 4 ton heavy satellitesv
  1. A. GSAT- 13
  2. B. GSAT- 14
  3. C. GSAT-17
  4. D. Way par GSAT-19
Solution

(d) Way par GSAT-19

Answer:

(d) Way par GSAT-19

2II. Fill in the blanks1 questions
Q.G1Waxing of Moon means _______ Heliocentric model is proposed by _______ _______ is the prevailing model of Evolution of the Universe. _______ is a large constellation which covers a large part of the sky. _______ is the first satellite launched by Indiav
Solution

growing or expanding
Nicolus copernicus
The Big Bang Theory
Ursa Major
Aryabhatta

Answer:

growing or expanding
Nicolus copernicus
The Big Bang Theory
Ursa Major
Aryabhatta

3III. True or False – If False give the correct answer5 questions
Q.1On a full Moon day, when the Sun is setting in the west, Moon rises in the West.v
Solution

False Correct statement: On a full Moon day, when the Sun is setting in the west, Moon rises in the East

Answer:

False Correct statement: On a full Moon day, when the Sun is setting in the west, Moon rises in the East

Q.2The word crescent refers to the phases where the Moon is less than half illuminated.v
Solution

True.
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Answer:

True.
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Q.3Galilio accepted the Geo-centric model.v
Solution

False
Correct statement: Galilio did nof accepted the Geo-centric model.

Answer:

False
Correct statement: Galilio did nof accepted the Geo-centric model.

Q.4Our Milky Way galaxy is identified as an elliptical galaxy.v
Solution

False Correct statement: Our Milky Way galaxy is identified as an galaxy.

Answer:

False Correct statement: Our Milky Way galaxy is identified as an galaxy.

Q.5The planet Venus in our solar system doesn’t have a Moon.v
Solution

True

Answer:

True

4IV. Match the following:1 questions
Q.G21. Rohini GSLV-Mark III 2. GSAT-14 GSLV Mark III D l 3. GSAT-19 SLV-3 4. Chandrayaan-2 PSLV-XL C25 5. Mangalyaan GSLV-D5v
Solution

1.
Rohini
SLV-3
2.
GSAT-14
GSLV-D5
3.
GSAT-19
GSLV Mark III D1
4.
Chandrayaan-2
GSLV-Mark III
5.
Mangalyaan
PSLV-XL C25

Answer:

1.
Rohini
SLV-3
2.
GSAT-14
GSLV-D5
3.
GSAT-19
GSLV Mark III D1
4.
Chandrayaan-2
GSLV-Mark III
5.
Mangalyaan
PSLV-XL C25

5V. Analogy:2 questions
Q.1Older stars : elliptical galaxies :: younger stars : ___________v
Solution

Irregular galaxies.

Answer:

Irregular galaxies.

Q.2Nearest galaxy: Andromeda :: Nearest star : ___________v
Solution

Alpha Centauri.
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Answer:

Alpha Centauri.
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6VI. Very short answer:7 questions
Q.1The word _______ refers to the phases where the Moon is less than half illuminated (cresent / gibbous)v
Solution

cresent.

Answer:

cresent.

Q.2___________ and ___________ planets never appear in the mid-night sky.v
Solution

Mercury, Venus.

Answer:

Mercury, Venus.

Q.3Number of days taken by the Mars to orbit around the Sun.v
Solution

687 days.

Answer:

687 days.

Q.4In which phase does the size of the planet Venus is small?v
Solution

When it was in Gibbous phase.

Answer:

When it was in Gibbous phase.

Q.5The only evidence of the big bang theory isv
Solution

The only evidence of the big bang theory is a faint glow in space, called cosmic microwave background.
SamacheerKalvi.Guru

Answer:

The only evidence of the big bang theory is a faint glow in space, called cosmic microwave background.
SamacheerKalvi.Guru

Q.6The galaxy which contains abundant amount of gas and dust is ___________ ?v
Solution

Spiral galaxy.

Answer:

Spiral galaxy.

Q.7Which country launched the world’s first artificial launch vehicle?v
Solution

Russia launched the world’s first artificial launch vehicle.

Answer:

Russia launched the world’s first artificial launch vehicle.

7VII. Short Answer Questions:3 questions
Q.1What is epicyclic model?v
Solution

To explain the puzzling phenomena astronomers in early times proposed a change in the simple geocentric model. This is called as epicycle model.
A small circle whose centre is on the circumference of a larger circle, in ptolemic astronomy.
It was seen as the basis of revolution of the seven plants, given a fixed central Earth.

Answer:

To explain the puzzling phenomena astronomers in early times proposed a change in the simple geocentric model. This is called as epicycle model.
A small circle whose centre is on the circumference of a larger circle, in ptolemic astronomy.
It was seen as the basis of revolution of the seven plants, given a fixed central Earth.

Q.2Name the four different types of Galaxies.v
Solution

Spiral galaxy
Elliptical galaxy
Irregular galaxy
Barred spiral galaxy

Answer:

Spiral galaxy
Elliptical galaxy
Irregular galaxy
Barred spiral galaxy

Q.4Give the expansions of PSLV and GSLV.v
Solution

PSLV : Polar Satellite Launch Vehicle.
GSLV : Geosynchronous Satellite Launch Vehicle.

Answer:

PSLV : Polar Satellite Launch Vehicle.
GSLV : Geosynchronous Satellite Launch Vehicle.

8VIII. Answer in Detail:2 questions
Q.1Explain the waxing and waning phases in Venus.v
Solution

As the Venus went around the epicycle, as shown in the diagram Venus would exhibit phases.
Also at times the planet would be nearer, making the apparent size grow bigger and at times far making the apparent size smaller.
If the Venus was going around the Sun, and its orbit is inside that of Earth, Venus would appear always near the Sun in the sky.
It can never be seen in the midnight sky. Two when it is near the Earth, it would be brighter and bigger compared to when it is on the other side of the Sun.
Thirdly only if the Venus is revolving around the Sun, it can exhibit gibbous phase, and the size of the gibbous phase smaller than the crescent phase.
If the Venus was revolving around the Earth, we can never see the gibbous phase of the Venus and it would be seen only if it is orbiting the Sun.
Samacheer Kalvi 7th Science Solutions Term 3 Chapter 2 Universal and Space

Answer:

As the Venus went around the epicycle, as shown in the diagram Venus would exhibit phases.
Also at times the planet would be nearer, making the apparent size grow bigger and at times far making the apparent size smaller.
If the Venus was going around the Sun, and its orbit is inside that of Earth, Venus would appear always near the Sun in the sky.
It can never be seen in the midnight sky. Two when it is near the Earth, it would be brighter and bigger compared to when it is on the other side of the Sun.
Thirdly only if the Venus is revolving around the Sun, it can exhibit gibbous phase, and the size of the gibbous phase smaller than the crescent phase.
If the Venus was revolving around the Earth, we can never see the gibbous phase of the Venus and it would be seen only if it is orbiting the Sun.
Samacheer Kalvi 7th Science Solutions Term 3 Chapter 2 Universal and Space

Q.2Write short notes on constellations.v
Solution

A constellation is a recognizable pattern of stars in the night sky when viewed from the Earth.
International Astronomical Union has classified 88 constellations to cover the entire celestial sphere.
Many of the old constellations have Greek or Latin names and are often named after mythological characters.
Ursa Major (Saptha Rishi Mandalam) is a large constellation and it covers a large part of the sky.
The most striking feature of this constellation is a group of seven bright stars known as big dipper (seven Sages in Indian astronomy).
Ursa Minor in Lattin means ‘the little bear’ it lies in the northern sky.
The Pole star – Polaris (Dhrua) lies within this constellation.
The main group, ‘little dipper’, consists of seven stars and is quite similar to that found in Ursa Major.

Answer:

A constellation is a recognizable pattern of stars in the night sky when viewed from the Earth.
International Astronomical Union has classified 88 constellations to cover the entire celestial sphere.
Many of the old constellations have Greek or Latin names and are often named after mythological characters.
Ursa Major (Saptha Rishi Mandalam) is a large constellation and it covers a large part of the sky.
The most striking feature of this constellation is a group of seven bright stars known as big dipper (seven Sages in Indian astronomy).
Ursa Minor in Lattin means ‘the little bear’ it lies in the northern sky.
The Pole star – Polaris (Dhrua) lies within this constellation.
The main group, ‘little dipper’, consists of seven stars and is quite similar to that found in Ursa Major.

9IX. HOT Question:1 questions
Q.1Neelan and Mala are having a conversation about our Universe. Neelan is telling our Earth will be the only planet in the entire Universe to have a life with. But, Mala is opposing his view by citing certain points. What would be the argument of Mala? Do you support Mala? Justify your stand.v
Solution

I would like to support Neelan, because Life is possible only on the Earth due to presence of water, oxygen, various gases and suitable temperature, which enables us to live.
Mala opposed Neelan’s view based on the following points :
Like the Sun, there might be billions of other stars with their own planets revolving around them.
Thus there are many chances of any planet getting the suitable conditions for supporting life.

Answer:

I would like to support Neelan, because Life is possible only on the Earth due to presence of water, oxygen, various gases and suitable temperature, which enables us to live.
Mala opposed Neelan’s view based on the following points :
Like the Sun, there might be billions of other stars with their own planets revolving around them.
Thus there are many chances of any planet getting the suitable conditions for supporting life.