Surajkund, the old reservoir near Faridabad, is believed to have been built by a ruler of which dynasty?

The correct answer is B, the Yamuna. The Yamuna comes down from Yamunotri, enters Haryana near Kalesar in Yamunanagar district and flows south along the eastern boundary of the state with Uttar Pradesh and Delhi. It is the only river in Haryana that carries water through the year, which is why the Hathnikund barrage and the canals drawn from it matter so much to the state's irrigation.

Option A, the Ghaggar, is the longest river inside Haryana but it is seasonal: it fills in the monsoon and runs as a sandy channel for the rest of the year, finally dying in the sands of Rajasthan. Option C, the Markanda, is a Shivalik stream and a tributary of the Ghaggar, dry outside the rains. Option D, the Sahibi, rises in the Aravalli of Rajasthan and reaches the Najafgarh jheel only in flood. The point to keep is the contrast: one perennial Himalayan river on the edge of the state, and seasonal streams everywhere else.

The correct answer is A, Yamunanagar. The Hathnikund barrage stands on the Yamuna in Yamunanagar district, where the river leaves the hills, and it replaced the older Tajewala headworks a short distance upstream. From it the Western Yamuna Canal carries water into Haryana and the Eastern Yamuna Canal into Uttar Pradesh, and the discharge released from it during heavy rain is what decides flood warnings downstream in Delhi.

Option B, Karnal, lies on the Yamuna further south and is a canal command district, not the site of the barrage. Option C, Panipat, is also on the river but is remembered for its three battles and its industry. Option D, Panchkula, is the district where the Ghaggar enters Haryana, so it belongs to the other river system altogether and is the most common distractor in this question. Remember the three names together: Tajewala, Hathnikund and the Western Yamuna Canal.

The correct answer is B, Panchkula. The Ghaggar rises in the Shivalik hills of Himachal Pradesh and comes into Haryana through Panchkula district in the extreme north-east, then turns south-west across Ambala, Kaithal, Fatehabad and Sirsa before passing into Rajasthan as the Hakra. Knowing the entry district also fixes the direction of the river's flow, which is the opposite of the Yamuna's.

Option A, Ambala, is the next district on its course and is often chosen by mistake because the Ghaggar and its tributary the Tangri are so closely associated with the town. Option C, Kaithal, and option D, Sirsa, are downstream districts; Sirsa is the last one before Rajasthan. In papers the Ghaggar is also asked as the state's longest river, as the classic case of inland drainage in north-west India, and as the river most scholars identify with the Vedic Saraswati.

The correct answer is C, the Ghaggar. Most scholars identify the Ghaggar, with its dry continuation the Hakra in Rajasthan and Pakistan, with the Saraswati of the Rigveda, and the neighbouring Chautang with the Drishadvati. The strongest support comes from archaeology: a very large number of Harappan settlements, among them Rakhigarhi in Hisar district and Banawali in Fatehabad, stand along these channels, which means they carried water when those towns were alive.

Option A, the Yamuna, is a living river with its own Vedic name and is thought by some to have captured part of the Saraswati's old drainage, but it is not the identification asked for. Option B, the Sahibi, is an Aravalli stream of south Haryana with no such association. Option D, the Markanda, is a tributary within the same Ghaggar system, so it is part of the answer's basin but not the river itself. Adi Badri in Yamunanagar district is the place traditionally treated as the Saraswati's source.

The correct answer is B, Yamunanagar. Adi Badri lies at the foot of the Shivaliks in Yamunanagar district, and tradition holds it to be the place where the Saraswati came down to the plain. It is the focus of the state's Saraswati heritage work, including the excavation and channelling of the old bed and the reservoir built in the hills above it.

Option A, Kurukshetra, is the heart of the Saraswati country in tradition, with Brahma Sarovar, Sannihit Sarovar and Jyotisar in it, so it is the most tempting wrong answer; but the source site is in Yamunanagar. Option C, Fatehabad, lies far downstream on the Ghaggar and holds the Harappan site of Banawali. Option D, Jhajjar, is in the south and is the district of the Bhindawas wetland. Remember the pair: Adi Badri in Yamunanagar for the source, Kurukshetra for the sacred tanks.