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The correct answer is A, Orange River. The Orange River is the longest river of South Africa, about 2,200 km long. It rises in the Drakensberg mountains of Lesotho, flows west across South Africa and falls into the Atlantic Ocean at Alexander Bay. For part of its course it forms the border between South Africa and Namibia. Its main tributary is the Vaal, and the Augrabies Falls lie on the Orange. The Limpopo is the other big river of South Africa, flowing east into the Indian Ocean. B is wrong because the Nile, the longest river in the world, flows north through countries such as Uganda, Sudan and Egypt into the Mediterranean Sea. C is wrong because the Congo flows through Central Africa, crosses the Equator twice and enters the Atlantic. D is wrong because the Niger flows through West Africa (Guinea, Mali, Niger and Nigeria) into the Gulf of Guinea. Exam tip: South Africa = Orange and Limpopo; Nile = north-east Africa; Congo = crosses the Equator twice; Niger = West Africa; Zambezi = Victoria Falls.

The correct answer is C, Panama Canal. The Panama Canal cuts across the narrow Isthmus of Panama in Central America and joins the Atlantic Ocean, through the Caribbean Sea, with the Pacific Ocean. It was opened in 1914 by the United States and is about 82 km long. Because the land in between is higher than the sea, ships are raised and lowered by locks that use water from the man-made Gatun Lake. The canal saves ships the long voyage around Cape Horn at the southern tip of South America. The USA handed the canal over to Panama on 31 December 1999. A is wrong because the Kiel Canal in Germany joins the North Sea and the Baltic Sea. B is wrong because the Suez Canal in Egypt, opened in 1869, joins the Mediterranean Sea and the Red Sea. D is wrong because the White Sea Canal in Russia links the White Sea with the Baltic Sea. Exam tip: Suez 1869 (Mediterranean to Red Sea, no locks), Panama 1914 (Atlantic to Pacific, with locks), Kiel (North Sea to Baltic Sea).

The correct answer is C, southern. Indira Point, the southernmost point of India, lies at the southern tip of Great Nicobar Island in the Andaman and Nicobar Islands. It is at about 6°45' North latitude. Its old name was Pygmalion Point, and it was renamed in 1985 in memory of Prime Minister Indira Gandhi. The southernmost point of mainland India is Kanyakumari in Tamil Nadu, at about 8°4' N. The Six Degree Channel, south of Great Nicobar, separates India from Sumatra in Indonesia. A is wrong because the northern tip of Great Nicobar faces Little Nicobar, the next island in the chain. B is wrong because the eastern coast runs along the side of the island and does not reach its southern end. D is wrong because the western coast also runs along the side of the island, not at its southern end. Exam tip: India's extreme points: south = Indira Point, mainland south = Kanyakumari, east = Kibithu (Arunachal Pradesh), west = Guhar Moti (Kutch, Gujarat).

The correct answer is D, Aravalli Range. Guru Shikhar, about 1,722 m high on Mount Abu in the Sirohi district of Rajasthan, is the highest peak of the Aravalli Range. The Aravallis are among the oldest fold mountains in the world and have been worn down into low hills. They run about 700 km from Gujarat through Rajasthan and Haryana to Delhi, where the Delhi Ridge is their last part. The range acts as a barrier to the spread of the Thar Desert towards the east, and Mount Abu is the only hill station of Rajasthan. A is wrong because the Vindhyas are a lower range in central India and Guru Shikhar is not part of them. B is wrong because the highest peak of the Western Ghats is Anamudi (2,695 m) in Kerala. C is wrong because the highest peak of the Satpura Range is Dhupgarh, near Pachmarhi in Madhya Pradesh. Exam tip: Aravalli = Guru Shikhar, Satpura = Dhupgarh, Western Ghats = Anamudi, Nilgiris = Doddabetta.

The correct answer is C, Mizoram. The NCERT Class 11 geography book describes Mizoram as the 'Molassis basin', made up of soft, unconsolidated deposits. Molasse is a geologists' word for soft sediments washed down from rising mountains and laid down in a basin; in Mizoram these young rocks were later folded into the north–south ridges of the Purvanchal hills that run along India's eastern border. Because the rocks are soft, the hills of Mizoram are prone to landslides in the monsoon. The Purvanchal also includes the Patkai hills, the Naga hills and the Manipur hills, and the Barak is an important river of Manipur and Mizoram. A is wrong because Tripura is not the state given this name. B is wrong because Assam is mostly the flat Brahmaputra valley. D is wrong because the Meghalaya plateau, with the Garo, Khasi and Jaintia hills, is an old block of hard rock that belongs to the Peninsular plateau. Exam tip: NCERT line: Mizoram = 'Molassis basin'; Meghalaya = detached part of the Peninsular plateau.