As seen from the Earth, a solar eclipse occurs when the Moon passes between the Sun and Earth, and the Moon fully or partially blocks the Sun. This can happen only at new moon, when the Sun and the Moon are in conjunction as seen from Earth. In a total eclipse, the disk of the Sun is fully obscured by the Moon. In partial and annular eclipses only part of the Sun is obscured.

Correct Option: B

As seen from the Earth, a solar eclipse occurs when the Moon passes between the Sun and Earth, and the Moon fully or partially blocks the Sun. This can happen only at new moon, when the Sun and the Moon are in conjunction as seen from Earth. In a total eclipse, the disk of the Sun is fully obscured by the Moon. In partial and annular eclipses only part of the Sun is obscured.

A traveler crossing the International Date Line eastbound subtracts one day, or 24 hours, so that the calendar date to the west of the line is repeated. Crossing the IDL westbound results in 24 hours being added, advancing the calendar date by one day. The International Date Line is necessary to have a fixed, albeit arbitrary, boundary on the globe where the calendar date advances in the westbound direction.

Correct Option: A

A traveler crossing the International Date Line eastbound subtracts one day, or 24 hours, so that the calendar date to the west of the line is repeated. Crossing the IDL westbound results in 24 hours being added, advancing the calendar date by one day. The International Date Line is necessary to have a fixed, albeit arbitrary, boundary on the globe where the calendar date advances in the westbound direction.

Because the density of pure ice is about 920 kg/ m³, and that of sea water about 1025 kg/m³, typically only one-ninth of the volume of an iceberg is above water.

Correct Option: A

Because the density of pure ice is about 920 kg/ m³, and that of sea water about 1025 kg/m³, typically only one-ninth of the volume of an iceberg is above water.

Overgrazing is the major cause of desertification worldwide. Plants of semi-arid areas are adapted to being eaten by sparsely scattered, large, grazing mammals which move in response to the patchy rainfall common to these regions. Early human pastoralists living in semi-arid areas copied this natural system. They moved their small groups of domestic animals in response to food and water availability. Such regular stock movement prevented overgrazing of the fragile plant cover.

Correct Option: B

Overgrazing is the major cause of desertification worldwide. Plants of semi-arid areas are adapted to being eaten by sparsely scattered, large, grazing mammals which move in response to the patchy rainfall common to these regions. Early human pastoralists living in semi-arid areas copied this natural system. They moved their small groups of domestic animals in response to food and water availability. Such regular stock movement prevented overgrazing of the fragile plant cover.

The circumference of the earth at the equator is 24,901.55 miles (40,075.16 kilometers). But, if we measure the earth through the poles the circumference is a bit shorter - 24,859.82 miles (40,008 km). Thus, the earth is a tad wider than it is tall, giving it a slight bulge at the equator. This shape is known as an ellipsoid or more properly, geoid (earth-like).

Correct Option: C

The circumference of the earth at the equator is 24,901.55 miles (40,075.16 kilometers). But, if we measure the earth through the poles the circumference is a bit shorter - 24,859.82 miles (40,008 km). Thus, the earth is a tad wider than it is tall, giving it a slight bulge at the equator. This shape is known as an ellipsoid or more properly, geoid (earth-like).