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#### Question 1:

Study the flowchart given below and identify the objects A, B, C and D.
(a) A-sun; B-asteroid; C-moon; D-INSAT2D
(b) A-moon; B-asteroid; C-Venus; D-INSAT2D
(c) A-sun; B-asteroid; C-comet; D-moon
(d) A-sun, B-comet; C-INSAT2D; D-moon
figure

#### Answer:

(d) A - sun; B - comet; C - INSAT2D; D - moon

A -Sun (It has its own light.)
B - Comet (It does not revolve around the earth.)
C - INSAT2D (It is an artificial satellite.)
D - Moon (It completes its rotation around the earth in 29 days.)

#### Question 2:

It was a full moon night in Delhi on 15 September 2008. Was it also a full moon night in Punjab and in London?
(a) It was a full moon night in Punjab and London.
(b) It was a full moon night in Punjab but not in London.
(c) It was full moon night in London but not in Punjab.
(d) It was not a full moon night in either Punjab or London.

#### Answer:

(a) It was a full moon night in Punjab and London.

A full moon is the lunar phase that occurs when the moon is completely illuminated as seen from all parts of the earth.

#### Question 3:

Why doesn't the moon appear as bright in the daytime as it does at night?
(a) The moon receives less sunlight
(b) The sunlight makes the moon appear less bright.
(c) The moon does not reflect light in the daytime.
(d) The moon reflects a lot of light from the sun.

#### Answer:

(b) The sunlight makes the moon appear less bright.

The light in the atmosphere, i.e., sunlight, brings about this difference.

#### Question 4:

Study the table in Exercise 5 on page 218. How many planets listed in the table have a larger diameter than that of the earth?
(a) 2
(b) 3
(c) 4
(d) 5

#### Answer:

(b) 3

According to the table, the planets Jupiter, Saturn and Neptune have larger diameters than the earth.

#### Question 5:

The phases of the moon are produced by
(a) the spin of the earth.
(b) varying amounts of sunlight reaching the side of the moon that faces the earth.
(c) the revolution of moon around the earth.
(d) the revolution of the earth around the moon.

#### Answer:

(b) varying amounts of sunlight reaching the side of the moon that faces the earth

The changes in the shape and size of the moon are called its phases, and they occur because of the way the sun shines on it.

#### Question 6:

The period from one new moon to the next is complete in about a month because in that time
(a) the earth rotates once on its axis.
(b) the earth revolves once around the sun.
(c) the earth completes half a revolution.
(d) the moon revolves once around the earth.

#### Answer:

(d) the moon revolves once around the earth

The moon takes 29 days to rotate on its axis and the same time to orbit the earth.

#### Question 7:

Which of these pictures best shows the correct position of the earth, moon and the sun with respect to each other?
figure

#### Answer:

Picture 'd' best shows the correct positions of the earth, the moon and the sun with respect to one another.
The earth revolves around the sun, and the moon revolves around the earth.

#### Question 8:

Given below is a diagram showing a solar eclipse. In which of the places shown on the earth will a partial solar eclipse by visible?
figure

#### Answer:

A partial solar eclipse is visible from within the moon's penumbral shadow, i.e., from places b, c and d.

#### Question 9:

Carefully study the table on page 218 that shows the average distance of the planets from the sun. If the planets were on the same side of the sun, which line correctly shows the position of the planets and their distance with respect to the sun?
graphic

#### Answer:

Here, line (a) correctly shows the positions of the planets and their distances with respect to the sun.

#### Question 10:

On a full moon day
(a) the side of the moon facing the earth receives no sunlight.
(b) the side of the moon facing the earth receives full sunlight.
(c) the moon is between the earth and the sun.
(d) the earth is between the sun and the moon.

#### Answer:

(d) the earth is between the sun and the moon

When the moon and the sun are on opposite sides of the earth, the sun shines directly on the moon's surface, resulting in a full moon.

#### Question 11:

Match the items in column I to those in column II.

 Column I Column II a. Polaris i. group of stars b. star ii. chunks of rocks or metal the fall to earth from space c. sunspots iii. a streak of light seen in the night sky d. meteor iv. star closest to the earth after the sun e. meteorite v. star closest to the earth after the sun f. asteroids vi. a small object that orbits a larger one g. constellation dark, cool patches on the sun h. Proxima Centauri vii. dark, cool patches on the sun i. satellite ix. rocks found between Jupiter and Mars j. prominences x. objects that give out their own light

#### Answer:

 Column I Column II a. Polaris v. a star that appears stationary b. Star x. objects that give out their own light c. Sunspots vii. dark, cool patches on the sun d. Meteor iii. a streak of light seen in the night sky e.Meteorite ii. chunks of rocks or metal that fall to earth from space f. Asteroids ix. rocks found between Jupiter and Mars g. Constellation i. group of stars h. Proxima Cenaturi iv. star closest to the earth after the sun i. Satellite vi. a small object that orbits a larger one j. Prominences viii. great swirls of hot gases that leap out of the sun

#### Question 12:

Differentiate between:
(a) a star and a planet
(b) a comet and an asteroid
(c) sunspots and prominences
(d) a meteor and a meteorite

#### Answer:

(a) A star and a planet

 Star Planet It has its own light. It does not have its own light; it shines owing to the reflection of light from the sun. It is a ball of gases. It is a small, solid body. There are billions of stars in the space. There are only eight planets in the solar system. Stars are very far from the earth. The planets are closer than the stars.

(b) A comet and an asteroid
 Asteroid Comet Asteroids are made up of metals and rocky material. Comets are made up of ice, dust and rocky material. Asteroids are formed much closer to the sun, where it is too warm for ice to remain solid. Comets are formed farther from the sun where ice would not melt. Asteroids tend to have shorter, more circular orbits, and they seem to want to group together in belts. Comets tend to have very extended and elongated orbits.

(c) Sunspots and prominences
 Sunspots Prominences Sunspots are small, dark patches on the sun. Prominences are great swirls of hot gases that leap out of the sun's surface.

(d) A meteor and a meteorite
 Meteor Meteorite A meteor is a burning rock from outer space that we see streaking across the sky. A meteorite is a rock from outer space that was once a meteor and has fallen to the earth.

#### Question 13:

Explain with the help of a neat labelled diagrams the occurrence of solar and lunar eclipses.

#### Answer:

Solar eclipse
A solar eclipse is an eclipse of the sun. It happens when the moon passes directly between the earth and the sun, casting a shadow on the surface of the earth.

Lunar eclipse
A moon eclipse or lunar eclipse is an eclipse of the moon. It occurs when the earth passes directly between the sun and the moon. Areas of the moon on which the earth's shadow falls do not receive and reflect sunlight.

#### Question 14:

Give reasons for the following:
(a) We always see the same side of the moon.
(b) Eclipses do not occur on every new moon.
(c) Meteors glow red hot as they enter the earth's atmosphere.

#### Answer:

(a) From the earth, we always see the same face of the moon because the moon takes 29 days to rotate on its axis and the same time to orbit the earth.

(b) Eclipses occur when the sun moon and the earth lie on the same plane. Eclipses do not occur on every new-moon night because the moon's orbit around the earth is tilted. Their orbits do not lie on the same flat plane on every new-moon night.

(c) As meteors enter the earth's atmosphere, they become red hot and burn because of friction with the atmosphere.

#### Question 15:

Arrange the pictures showing the phases of the moon in the correct order starting from the new moon to the full moon.
figure

#### Answer:

The correct order of the phases of the moon from new moon to full moon is given by
$\to$$\to$ b $\to$$\to$$\to$$\to$$\to$ e

#### Question 16:

Find the odd one out in the following groups and give reasons for your answers.
(a) Cassiopeia, Milky Way, Orion, Ursa Major
(b) Sun, Proxima Centauri, Polaris, Mercury
(c) Moon, Mars, Saturn, Neptune

#### Answer:

(a) Milky Way
Here, the Milky Way is the galaxy that contains our solar system; all the others fall under the category of constellations.

(b) Mercury
Mercury is a planet of our solar system; all the others are stars.

(c) Moon
The moon is the only natural satellite of the earth; all the others are planets of our solar system.

#### Question 17:

Rewrite the incorrect statements correctly.
(a) The earth is a satellite of the sun.
(b) The Pole Star is used by sailors to fix the position of ships.
(c) The orbits of the planets around the sun are circular.
(d) The sun's  gravity prevents the planets from flying off into space.
(e) The moon goes through a complete cycle of waxing and waning in 14 days.
(f) Meteors glow because of friction when they enter the atmosphere.
(g) Solar eclipses occurs when the shadow of the moon false on the earth.
(h) The revolution of the earth causes day and night.

#### Answer:

(a) The earth is a satellite of the sun.
Correct

(b) Incorrect

The Pole Star is used by sailors to measure the latitude of a place.

(c) Incorrect

The orbits of the planets around the sun are elliptical.

(d) The sun’s gravity prevents the earth and the other planets from flying off into deep space.
Correct

(e) Incorrect

The moon goes through a complete cycle of waxing and waning about every 29 days.

(f) Incorrect

Meteors become red hot and burn up because of friction with the atmosphere.

(g) A solar eclipse occurs when the moon's shadow falls on the earth.
Correct

(h) Incorrect

The rotation of earth on its axis causes day and night.

#### Question 18:

Give a word/phrase for each of the following:
(a) a group of stars that move together
(b) a dark, cooler spot on the sun
(c) when the earth's shadow falls on the moon
(d) the galaxy of which our solar system forms a part
(e) bright heavenly body with a long tail
(f) the effect caused by sunspots
(g) phase of the moon when it is totally dark except for a thin outline
(h) the largest planet
(i) the evening star

#### Answer:

(a) Constellation
(b) Sunspot
(c) Lunar eclipse
(d) Milky Way
(e) Comet
(f) Solar prominences
(g) New moon
(h) Jupiter
(i) Venus

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