Answer: (C)

Explanation: The monsoons are experienced in the tropical area roughly between 20° N and 20° S. To understand the mechanism of the monsoons, the following facts are important:

1. The differential heating and cooling of land and water creates low pressure on the landmass of India while the seas around experience comparatively high pressure.
2. The shift of the position of Inter Tropical Convergence Zone (ITCZ) in summer, over the Ganga plain (this is the equatorial trough normally positioned about 5°N of the equator – also known as the monsoon trough during the monsoon season).
3. The presence of the high-pressure area, east of Madagascar, approximately at 20°S over the Indian Ocean. The intensity and position of this high-pressure area affects the Indian Monsoon.
4. The Tibetan plateau gets intensely heated during summer, which results in strong vertical air currents and the formation of high pressure over the plateau at about 9 km above sea level.
5. The movement of the westerly jet stream to the north of the Himalayas and the presence of the tropical easterly jet stream over the Indian peninsula during summer.

Hence, all statements are correct.

Answer: (C)

Explanation: Due to a low temperature in the winter season, a high pressure develops over north-western India. In contrast to it, low pressure is found over south India, Arabian Sea and Bay of Bengal. Therefore, winds blow from north-west to south-east. Hence, option (c) is correct.

Answer: (C)

Explanation: Jet streams are some of the strongest winds in the atmosphere. Their speeds usually range from 129 to 225 kilometers per hour, but they can reach more than 443 kilometers per hour. They are faster in winter when the temperature differences between tropical, temperate, and polar air currents are greater.

At most times in the Northern and Southern Hemispheres, there are two jet streams: a subtropical jet stream centered at about 30 degrees latitude and a polar-front jet stream whose position varies with the boundary between polar and temperate air. A reverse jet stream blows toward the west in tropical high altitudes during the Northern Hemispheres summer. It is associated with the heating of the Asian continent and may help bring summer monsoons to the Indian Ocean. Hence, all statements are correct.

Answer: (A)

Explanation: The Big Bang Theory considers the following stages in the development of the universe.

1. In the beginning, all matter forming the universe existed in one place in the form of a “tiny ball” (singular atom) with an unimaginably small volume, infinite temperature and infinite density.
2. At the Big Bang the “tiny ball” exploded violently. This led to a huge expansion. It is now generally accepted that the event of big bang took place 13.7 billion years before the present. The expansion continues even to the present day. As it grew, some energy was converted into matter. There was particularly rapid expansion within fractions of a second after the bang. Thereafter, the expansion has slowed down. Within first three minutes from the Big Bang event, the first atom began to form.
3. Within 300,000 years from the Big Bang, temperature dropped to 4,500K (Kelvin) and gave rise to atomic matter. The universe became transparent.

Hence, statement 2 is incorrect.

Answer: (C)

Explanation: The troposphere is thicker at the equator than at the poles because the equator is warmer. The convection currents of air expand the thickness of the troposphere (atmosphere). Thus the simple reason is thermal expansion of the atmosphere at the equator and thermal contraction near the poles. Also, the rotation of the earth causes centrifugal force which is strongest near the equator and pushes the atmosphere to greater heights. The thickness of the troposphere also varies with season. The troposphere is thicker in the summer and thinner in the winter all around the planet. Hence, both statements are correct.