ICSE CLASS 9

GEOGRAPHY
IMPORTANT QUESTION ANSWER

Provide three pieces of evidence which prove the Earth is spherical in the shape.

Ans. The three pieces of evidence that prove the Earth is flat are as follows:

Sighting of a ship: While standing at seashore, watching an approaching ship, we first of all see only its mast. Then, as it comes closer, we can see the deck in the middle, then its funnel, and finally the hull comes into full view. This can happen only when the earth's surface is curved। If the earth were flat, the entire ship would have been seen all at once.

The Bedford Level Experiment: Almost on similar lines, as described above, an experiment was carried out in the Bedford Level canal area in England. Three poles of equal length were fixed at intervals of 5 km. It was ensured that the poles had the same height above the water in the canal. When the poles were viewed from one end of the canal, the middle pole looked slightly higher. It could not have happened if the earth had a flat surface. A similar experiment was repeated at different places . It sufficiently demonstrated that the surface of the earth was curved।

Sunrise and Sunset: The sun rises from the east and sets in the west. Sunrise and sunset occurs at different times at different places. This is because the earth rotates from west to east and therefore, people in the east can see the sun earlier than those in the west. Had the earth been flat, the sunrise and sunset would have occurred at the same time all over the world.

How the position of the pole star gives indication that the earth was spherical in shape.

Ans. Pole Star: The Pole star can be seen at an angle of 90° at the North Pole. It lies in line with the axis of the earth, and its angle decreases towards the Equator. At the Equator, the angle is 0°. This can happen only in an arc of a circle.

State how the atmosphere of the Earth is different from those of the other planet.

Ans. The atmospheric blanket of Earth contains 78 percent of nitrogen and 21% of oxygen along with a minimal percentage of water and carbon dioxide. The mixture is quite different to that of the atmosphere of other planet in the solar system. Jupiter and Saturn are dominated by hydrogen and helium whereas the Venus and the Mars contain 96 percent of carbon dioxide and only 3% nitrogen, The atmosphere of mercury contains a large percentage of hydrogen, helium and oxygen and a small percentage of potassium, sodium, calcium and magnesium.

State three importance of atmosphere.

Ans. The atmosphere is essential for us because

(i) It is indispensable for the sustenance of living beings, as it contains oxygen and other necessary gases.

(ii) It plays a vital role in the water cycle, as most of the process is being carried out in the lower atmosphere.

(iii) It prevents excess heat and harmful radiation from reaching the surface of the earth.

Name three factors which have made earth a habitable?

Ans. The factors that made the earth habitable are

(1) The distance from the Sun is just optimum and thus it helps in maintaining the average surface temperature of 17°C.

(ii) The gaseous envelop known as the atmosphere that contains the important gases such as oxygen which facilitates life. It also protects the surface from the heat and harmful radiations.

(iii) It provides necessary nutrients for the growth and sustenance of life.

Write three importance of lithosphere.

Ans The lithosphere is important to us because: (i) It is the hard crust where all the activities of animal and plant kingdom take place.

(ii) It contains various minerals and nutrients which are essential for the sustenance of life. (iii) It contains huge water bodies which satisfy our demand for water and energy supply.

Mention three important features of the Earth that supports life.

Ans. The features that support life on Earth are as follows:

(i) Earth's Atmosphere: The Earth is surrounded by an atmosphere which contains valuable gases such as nitrogen, oxygen and traces of other gases essential for living. The atmosphere helps the Earth to maintain a mean average temperature of 17°C that supports life.

(ii) The distance from the sun: The distance of the Earth from the Sun is neither too far or too near.It is at such a distance that it receives the right amount of heat which is conducive for life.

(iii) Presence of ozone in the atmosphere: The stratosphere around the earth contains the ozone which absorbs the high-frequency ultra-violate rays that are harmful to us. It also retains the heat radiated from the surface of Earth.

Write a brief note about the Solar systems.

Ans. (1) The solar system consists of 8 planets, revolving around the Sun. It also consists of satellites which revolve around planets, asteroids, comets, gases and dust.

(ii) Based on the distance from the Sun the planets are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune

(iii) The planets of the solar systems are divided into two groups: inner and outer planets. The group of planets close to the Sun are known as inner planets such as Mercury, Venus, Mars and Earth. The group of planets which are far away from the Sun are known as outer planets such as Jupiter, Saturn, Uranus and Neptune. The inner group of planets are made of rocks whereas the outer planets are made of large balls of gases

Why does the earth have optimum temperature condition?

Ans. The Earth is the only planet is the solar system, which has an optimum temperature that sustains life on it. The significant reason are as follows:

(i) The planet is situated neither too close nor too far from the Sun. The distance is just too right to maintain an average temperature of 14°C on the Earth surface. The Zone of the optimum range is called the Goldilocks Zone.

(ii) The second most important reason is the atmospheric blanket that covers the Earth. The atmosphere protects us from the Sun's excessive heat and harmful radiation. It also helps in trapping the heat that radiates back from the Earth and keeps it warm.

What do you understand antipodal balance between land and water?

Ans

(i) There is an antipodal balance between land and water on directly opposite side of the Earth. Land and one side of the globe is balanced by water on the other side of the Earth. For instance North Pole Arctic Ocean is opposite to the continent of Antarctica.

(ii) The Northern Hemisphere is girdled by the large land masses of North America and Eurasia.

(iii) In the South Hemisphere are the continents of South America, Africa and Australia.

(iv) The landmass of Antarctica had three Prominent protruding area one towards South America, another towards South Africa and third towards Australia.