Which belt of the Northern Plains is a narrow strip of pebbles at the foot of the Shiwaliks, in which streams disappear from the surface?

The correct answer is C, Himadri or Greater Himalaya. The Himadri is the innermost and northernmost of the three parallel Himalayan ranges, with an average height of about 6,000 metres. It is the most continuous of the three, carries the loftiest peaks and stays under snow through the year, which is why the largest Himalayan glaciers, such as Gangotri and Yamunotri, lie in it. Option A is wrong because the Shiwalik is the outermost and lowest range, only about 900 to 1,100 metres high and built of loose sediment washed down by rivers. Option B is wrong because the Himachal or Lesser Himalaya lies between the other two, at about 3,700 to 4,500 metres, and holds the hill stations and the Kashmir, Kangra and Kullu valleys. Option D is wrong because the Purvanchal hills are the eastern extension beyond the Brahmaputra bend, not one of the three parallel ranges.

The correct answer is B, Shiwalik and Lesser Himalaya. Duns are flat-floored longitudinal valleys formed where rivers coming out of the Lesser Himalaya were held up behind the rising Shiwalik and filled the depression with gravel and silt. Dehra Dun in Uttarakhand is the largest, and Kotli Dun and Patli Dun are the other examples exams name. Option A is wrong because the valley belt between the Greater and the Lesser Himalaya includes the Kashmir valley, which is filled with Karewa lake deposits rather than being called a Dun. Option C is wrong because the Karakoram and the Ladakh range lie in the Trans-Himalayan zone north of the Greater Himalaya, where the Indus flows between them. Option D is wrong because the Zaskar range also belongs to the Trans-Himalayan system and holds no Duns.

The correct answer is A, Saffron. Karewas are thick beds of glacial clay, silt and other lake sediments laid down in the Kashmir valley, which lies between the Pir Panjal and the Greater Himalaya. Their fine, well-drained soil and the valley's cold winters suit saffron, and the Pampore area near Srinagar is the best-known growing tract; almond and apple orchards also stand on these deposits. Option B is wrong because tea needs a warm, humid climate with heavy, well-distributed rainfall and grows in Assam, the Darjeeling hills, the Nilgiris and Kerala. Option C is wrong because rubber is an equatorial crop grown mainly in Kerala, Tamil Nadu, Karnataka and the north-eastern states. Option D is wrong because jute needs the hot, humid alluvial flood plains of West Bengal, Bihar and Assam, not a cold mountain valley.

The correct answer is C, Bhangar. Bhangar is the older alluvial deposit of the Northern Plains. It forms terraces that stand above the present flood level, so fresh silt no longer reaches it, and long leaching has left calcareous concretions called kankar in its profile. Being less often renewed, it is the less fertile of the two alluviums. Option A is wrong because Khadar is the newer alluvium of the flood plains, renewed by almost every flood and therefore more fertile. Option B is wrong because Bhabar is the pebble belt at the foot of the Shiwaliks where streams disappear underground. Option D is wrong because Terai is the marshy, once heavily forested strip south of the Bhabar where those streams come back to the surface. Candidates often reverse Bhangar and Khadar, so fix that Bhangar is the older one.

The correct answer is D, Sikkim. Nathu La lies in eastern Sikkim on the old trade route from Gangtok to Lhasa and is one of the passes on India's border with the Tibet region of China; Jelep La, also in Sikkim, is the other. Option A is wrong because the passes of Himachal Pradesh are Rohtang, Baralacha La and Shipki La, the last carrying the Satluj across the border. Option B is wrong because Uttarakhand's passes are Mana, Niti and Lipulekh, used historically by pilgrims and traders. Option C is wrong because Arunachal Pradesh has Bomdi La and Bum La, the latter on the line facing Tibet near Tawang. Questions on this topic usually ask you to match a pass with its state, so it helps to group them state by state before the exam.