Answer: (B)

Explanation: Conditions favourable for the formation of deltas:
1. Lateral erosion and vertical erosion in the upper course of the river to provide extensive sediments to be eventually deposited as deltas.
2. The coast should be sheltered and preferably without tides.
3. The sea should be shallow near the delta region or else the load will disappear in the deep water.
4. There should not be the presence of large lakes in the river course to filter off the sediments.
5. The currents should be weak and no strong current should run at right angles to the river mouth as it can wash the sediment away. Hence, statement 1 and 4 are correct.

Answer: (B)

Explanation: The pattern that can be identified in the location of the world’s deserts is that almost all the deserts are confined within 15 to 30 degrees parallels of latitude north and south of the equator. Hence, statement 1 is not correct. They lie in the trade wind belt on the western parts of the continents where Trade winds are off-shore. They are bathed by cold currents which produced a ‘desiccating effect’ so that moisture is not easily condensed into precipitation. Dryness or aridity is the key note. Such deserts are tropical hot deserts or ‘Trade wind deserts’. They include the Great Sahara Desert; Arabian, Iranian and Thar Deserts; Kalahari, Namib, and Atacama Deserts; the Great Australian Deserts and the deserts of the south-west U.S.A, and northern Mexico. In the continental interiors of the mid-latitudes, the deserts such as the Gobi and Turkestan are characterised by extremes of temperatures. Hence, statement 2 is correct.

Answer: (A)

Explanation: The plates act like a hard and rigid shell compared to Earth’s mantle. This strong outer layer is called lithosphere. Plate tectonics is the modern version of continental drift, a theory first proposed by scientist Alfred Wegener in 1912. Wegener didn’t have an explanation for how continents could move around the planet, but researchers do now. Plate tectonics is thus said to be the unifying theory of geology. The driving force behind plate tectonics is convection in the mantle. Hot material near Earth’s core rises, and colder mantle rock sinks. In terms of analogy, it is kind of a pot boiling on a stove. The convection drives plate tectonics through a combination of pushing and spreading apart at mid-ocean ridges and pulling and sinking downwards at subduction zones. Hence, only statement 2 is correct.

Answer: (A)

Explanation: The Big Bang Theory considers the following stages in the development of the universe.
(i) 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.
(ii) 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.
(iii) 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 not correct.

Answer: (B)

Explanation: The profundal zone is a deep zone of an inland body of freestanding water, such as a lake or pond, located below the range of effective light penetration. This is typically below the thermocline, the vertical zone in the water through which temperature drops rapidly. The profundal is often defined, as the deepest, vegetation-free, and muddy zone of the lacustrine benthal. The profundal zone is often part of the aphotic zone. Hence, option (b) is correct.