✅ Answer: B) Ganga (2,525 km)The Ganga is the longest river in India at 2,525 km. It originates from the Gangotri glacier in Uttarakhand (called Bhagirathi at source) and flows into the Bay of Bengal. The Indus is longer overall (2,900 km) but most of it flows through Pakistan. Godavari (1,465 km) is the longest peninsular river.

✅ Answer: B) Frequently changes course and causes floodsThe Kosi river is called the “Sorrow of Bihar” because it frequently changes its course (has shifted ~120 km westward over 200 years) and causes devastating floods in Bihar. It originates in Nepal and is a left bank tributary of the Ganga. The 2008 Kosi flood was one of the worst in Bihar’s history.

✅ Answer: B) Ravi, Beas, SutlejUnder the Indus Waters Treaty (1960), India gets the three eastern rivers: Ravi, Beas, and Sutlej. Pakistan gets the three western rivers: Indus, Jhelum, and Chenab. The treaty was mediated by the World Bank and has survived three wars between India and Pakistan. It is considered one of the most successful water-sharing treaties.

✅ Answer: C) BrahmaputraMajuli is the world’s largest river island, located in the Brahmaputra river in Assam. It became a district of Assam in 2016. It is known for its Vaishnavite monasteries (Satras) and unique culture. The island is shrinking due to erosion — it has reduced from ~1,250 sq km to ~875 sq km over the past century.

✅ Answer: B) Longest and most sacred peninsular riverThe Godavari (1,465 km) is called “Dakshin Ganga” (Ganga of the South) because it is the longest and most sacred peninsular river — like the Ganga in North India. It originates from Trimbakeshwar (Maharashtra) and flows into the Bay of Bengal. The Kumbh Mela is held at Nashik on the Godavari.

✅ Answer: C) NarmadaThe Narmada flows westward and forms an estuary (not a delta) where it meets the Arabian Sea. Tapi (Tapti) also flows westward and forms an estuary. Most peninsular rivers flow eastward and form deltas. Narmada flows through a rift valley between the Vindhya and Satpura ranges. Sardar Sarovar dam is on the Narmada.

✅ Answer: C) MahanadiThe Hirakud dam is built on the Mahanadi river in Odisha. It is the longest dam in India (~26 km). It was completed in 1957 and was one of the first major multipurpose river valley projects in India. The Mahanadi originates in Raipur (Chhattisgarh) and flows into the Bay of Bengal.

✅ Answer: B) Ganga and BrahmaputraThe Sundarbans delta is formed by the Ganga and Brahmaputra rivers. It is the world’s largest delta, shared between India (West Bengal) and Bangladesh. It is a UNESCO World Heritage Site and is famous for the Royal Bengal Tiger. The Sundarbans is the world’s largest mangrove forest.

✅ Answer: B) Tibet (China)The Brahmaputra is known as Tsangpo in Tibet, Dihang/Siang in Arunachal Pradesh, and Brahmaputra in Assam. In Bangladesh, it is called Jamuna. It originates from the Chemayungdung glacier in Tibet. The Dihang gorge (where it enters India) is the deepest gorge in the world (~5,500m deep).

✅ Answer: B) Karnataka and Tamil NaduThe Cauvery water dispute is between Karnataka (upper riparian state) and Tamil Nadu (lower riparian state). Karnataka wants to use more water for irrigation; Tamil Nadu depends on Cauvery water for the Cauvery delta (rice bowl). The Cauvery Water Disputes Tribunal was set up in 1990 and gave its final award in 2007. The Supreme Court modified it in 2018.