Solution: (b)

You may also see the moon on most of the days. It may, however, appear at different times, in different

shapes and at different positions. You can see the full moon only once in about a month’s time. It is

Full moon night or Poornima. A fortnight later, you cannot see it at all. It is a New moon night or

Amavasya. On this day, you can watch the night sky best, provided it is a clear night

Solution: (d)

Jupiter, Saturn and Uranus have rings around them. These are belts of small debris. These rings may

be seen from the earth with the help of powerful telescopes.

Solution: (c)

You will notice that a needle is fixed through the globe in a tilted manner, which is called its axis. Two points on the globe through which the needle passes are two poles – North Pole and South Pole. The globe can be moved around this needle from west to east just as the earth moves. But, remember there is a major difference. The real earth has no such needle. It moves around its axis, which is an imaginary line. Another imaginary line running on the globe divides it into two equal parts. This line is known as the equator. The northern half of the earth is known as the Northern Hemisphere and the southern half is known as the Southern Hemisphere. They are both equal halves.

Therefore, the equator is an imaginary circular line and is a very important reference point to locate places on the earth. All parallel circles from the equator up to the poles are called parallels of latitudes.

Latitudes are measured in degrees.

The equator represents the zero degree latitude. Since the distance from the equator to either of the poles is one-fourth of a circle round the earth, it will measure ¼th of 360 degrees, i.e. 90°. Thus, 90 degrees north latitude marks the North Pole and 90 degrees south latitude marks the South Pole.

Solution: (c)

Besides the equator (0°), the North Pole (90°N) and the South Pole (90° S), there are four important

parallels of latitudes–

(i) Tropic of Cancer (23½° N) in the Northern Hemisphere.

(ii) Tropic of Capricorn (23½° S) in the Southern Hemisphere.

(iii) Arctic Circle at 66½° north of the equator.

(iv) Antarctic Circle at 66½° south of the equator.

HEAT ZONES OF THE EARTH

The mid-day sun is exactly overhead at least once a year on all latitudes in between the Tropic of

Cancer and the Tropic of Capricorn. This area, therefore, receives the maximum heat and is called the

Torrid Zone.

The mid-day sun never shines overhead on any latitude beyond the Tropic of Cancer and the Tropic of Capricorn. The angle of the sun’s rays goes on decreasing towards the poles. As such, the areas bounded by the Tropic of Cancer and the Arctic Circle in the Northern Hemisphere, and the Tropic of Capricorn and the Antarctic Circle in the Southern Hemisphere, have moderate temperatures. These are, therefore, called Temperate Zones.

Areas lying between the Arctic Circle and the North Pole in the Northern Hemisphere and the Antarctic Circle and the South Pole in the Southern Hemisphere, are very cold. It is because here the sun does not rise much above the horizon. Therefore, its rays are always slanting and provide less heat. These are, therefore, called Frigid Zones (very cold)

Solution: (a)

Unlike parallels of latitude, all meridians are of equal length. Thus, it was difficult to number the meridians. Hence, all countries decided that the count should begin from the meridian which passed through Greenwich, where the British Royal Observatory is located. This meridian is called the Prime

Meridian. Its value is 0° longitude and from it we count 180° eastward as well as 180° westward.

The Prime Meridian and 180° meridian divide the earth into two equal halves, the Eastern Hemisphere and the Western Hemisphere. Therefore, the longitude of a place is followed by the letter E for the east and W for the west. It is, however, interesting to note that 180° East and 180° West meridians are on the same line.

Solution: (d)

Rotation is the movement of the earth on its axis. The movement of the earth around the sun in a fixed path or orbit is called Revolution.

The axis of the earth which is an imaginary line, makes an angle of 66½° with its orbital plane. The plane formed by the orbit is known as the orbital plane. The earth receives light from the sun. Due to the spherical shape of the earth, only half of it gets light from the sun at a time. The portion facing the sun experiences day while the other half away from the sun experiences night. The circle that divides the day from night on the globe is called the circle of illumination. This circle does not coincide with the axis. The earth takes about 24 hours to complete one rotation around its axis. The period of rotation is known as the earthday. This is the daily motion of the earth.

What would happen if the earth did not rotate? The portion of the earth facing the sun would always experience day, thus bringing continuous warmth to region. The other half would remain in darkness and be freezing cold all the time. Life would not have been possible in such extreme conditions.

The second motion of the earth around the sun in its orbit is called revolution. It takes 365¼ days (one year) to revolve around the sun. We consider a year as consisting of 365 days only and ignore six hours for the sake of convenience. A year is usually divided into summer, winter, spring and autumn seasons.

Seasons change due to the change in the position of the earth around the sun.

Solution: (d)

On 21st March and September 23rd, direct rays of the sun fall on the equator. At this position, neither of the poles is tilted towards the sun; so, the whole earth experiences equal days and equal nights. This is called an equinox.

Solution: (b)

The local time of places which are on different meridians are bound to differ. For example, it will be difficult to prepare a time-table for trains which cross several longitudes. In India, for instance, there will be a difference of about 1 hour and 45 minutes in the local times of Dwarka in Gujarat and Dibrugarh in Assam. It is, therefore, necessary to adopt the local time of some central meridian of a country as the standard time for the country. In India, the longitude of 82½° E (82° 30' E) is treated as the standard meridian. The local time at this meridian is taken as the standard time for the whole country. It is known as the Indian Standard Time (IST)

Answer: C

Explanation: Africa is the only continent which lies in all 4 hemispheres due to equator and Prime Meridian passing through the continent.

Answer: B

Explanation: Congo is the only river in the world that crosses equator twice.

Answer: D

Explanation: Great Barrier Reef, which is world heritage site has been threatened due to coral bleaching, a result of increasing temperatures of oceans caused by global warming. Coral bleaching occurs when algae is removed from coral polyps which otherwise has a symbiotic relationship

Answer: D

Australia is 2/3rd covered with deserts. Great Basin, Sonoran and Mojave are deserts of North America. Atacama and Patagonian are deserts of South America.

Answer: C

Explanation:

Grasslands in different areas take different names:

Pampas : Argentina

Prairies : North America

Downs : Australia

Steppes : Asia

Veld : Africa

Answer: D

Explanation: Inspite of its vast geographical extent, China decided to follow a single time zone for unifying its country and its people soon after the communist party assumed power.

Since all longitudes converge at North and South Pole, they have no time zone. Research stations follow the time of their countries or from where they set off their expedition.

ISS follows Greenwich Mean Time.

Answer: B

Explanation: Tropical deciduous forests care called monsoon forests because they shed their leaves during the dry season and bear leaves at the start of the rainy season or monsoon season.

Answer: C

Explanation: The oldest impact crater on Earth is also the largest. Vredefort crater in South Africa, also called the Vredefort Dome, was originally 185 miles (300 kilometers) across, scientists estimate. A meteorite or asteroid bigger than South Africa's Table Mountain blasted out the giant crater 2.02 billion years ago.