Which of the following is/are correct inference/inferences from isothermal maps in the month of January ? 1. The isotherms deviate to the north over the ocean and to the south over the continent. 2. The presence of cold ocean currents, Gulf Stream and North Atlantic Drift make the North Atlantic Ocean colder and the isotherms bend towards the north. Select the answer using the code given below :

The correct answer is C, Statement I is true but Statement II is false. Plantations do lie mostly in the humid tropics, but the soils there are generally poor, not highly fertile.

Plantation farming grows a single cash crop such as tea, coffee, rubber, sugarcane, cocoa, banana or oil palm on large estates with heavy capital and hired labour. It spread in the humid tropics of Asia, Africa and Latin America, largely under colonial rule, because these crops need high temperatures and heavy rain throughout the year. The same heavy rain leaches nutrients out of the soil, leaving laterite and other weathered red soils that are low in humus and plant food; the lush forest survives by quickly recycling nutrients from fallen leaves.

A is wrong: Statement II is false, so it cannot explain Statement I.

B is wrong: it treats the false Statement II as true.

D is wrong: Statement I is true and Statement II is false, the reverse of this option.

Exam tip: humid tropics have lush forest but leached, infertile laterite soil; plantations need the climate, not rich soil.

The correct answer is B, Only two. Mahua and teak shed their leaves in the dry season, while the jackfruit tree is evergreen.

Deciduous trees drop all their leaves for a few weeks in the dry summer to save water; they make up India's tropical moist and dry deciduous forests, the most widespread forest type in the country. Teak is the best-known tree of these forests, found in Madhya Pradesh, Maharashtra, Karnataka and Kerala. Mahua is a deciduous tree of central India whose flowers are eaten and used to make liquor, and whose seeds give oil; it matters greatly to tribal communities. The jackfruit, by contrast, keeps its glossy leaves all year and grows in the humid Western Ghats and coastal regions.

A is wrong because two of the trees, not one, are deciduous.

C is wrong because the jackfruit is evergreen.

D is wrong because teak and mahua are typical deciduous trees.

Exam tip: teak, sal, mahua, sandalwood = deciduous; jackfruit, rosewood, mahogany = evergreen.

The correct answer is D, All four. A volcanic eruption throws out solid fragments, fine ash and dust, and a mixture of gases that includes nitrogen and sulphur compounds.

Material released by a volcano is of three kinds. Solid matter includes pyroclastic debris, the broken pieces of rock and lava blown out by the explosion, ranging from large volcanic bombs to small lapilli, along with fine ash and dust that can spread across continents. Liquid matter is the lava. Gases are mostly water vapour, followed by carbon dioxide, sulphur compounds such as sulphur dioxide and hydrogen sulphide, and nitrogen compounds, with smaller amounts of chlorine, hydrogen and argon. Sulphur dioxide forms sulphate aerosols in the stratosphere that can cool the climate for a year or two.

A is wrong because more than one item is a volcanic product.

B is wrong because the gases, not only the solids, come from eruptions.

C is wrong because none of the four can be left out.

Exam tip: volcanic gases = mostly water vapour, then carbon dioxide, sulphur and nitrogen compounds.

The correct answer is B, Only two pairs. Pairs 1 and 2 are correct; Visakhapatnam is not India's largest container port.

Kamarajar Port at Ennore, near Chennai in Tamil Nadu, was the first major port in India to be set up as a corporate entity, registered as a public company (Ennore Port Ltd). Mundra Port in Kutch, Gujarat, run by the Adani group, is the largest privately owned port in India. Visakhapatnam in Andhra Pradesh is a major port known for iron ore and bulk cargo and has a deep natural harbour, but the biggest container traffic is handled on the west coast, at Jawaharlal Nehru Port (Nhava Sheva) and Mundra.

A is wrong because two pairs, not one, are correct.

C is wrong because pair 3 is incorrect.

D is wrong because pairs 1 and 2 are correctly matched.

Exam tip: Kamarajar (Ennore) = first corporatised major port; Mundra = largest private port; container giants are on the west coast.

The correct answer is A, both statements are correct and Statement-II explains Statement-I. The troposphere is thickest over the equator because strong convection there carries heat high into the air.

The troposphere, the lowest layer of the atmosphere where almost all weather occurs, is about 18 km thick at the equator but only about 8 km at the poles. Intense heating of the surface near the equator sets up powerful rising convection currents, which lift warm air and moisture to great heights and push the top of the layer, the tropopause, upward. Over the cold poles convection is weak, so the layer stays shallow. Temperature in the troposphere falls by about 6.5 °C per kilometre of height.

B is wrong because convection is exactly the reason for the greater thickness.

C is wrong because Statement-II is correct.

D is wrong because Statement-I is correct.

Exam tip: troposphere about 18 km at the equator, about 8 km at the poles, because of convection.