RAS question
Which is the longest river flowing entirely within Rajasthan?
Correct answer: (C) Banas.
Banas is the longest river flowing entirely within Rajasthan, with a total length of about 512 km.
Explanation
Banas is the right answer because the question is not asking for the largest or most famous river touching Rajasthan; it asks for the longest river whose course lies wholly inside the state. Banas, also known as Van ki Asha, is about 512 km long. India WRIS Wiki places the core geography clearly: Banas originates in the Khamnor hills of the Aravali range, flows along its entire length through Rajasthan, and meets the Chambal near village Rameshwar in Khandar Block of Sawai Madhopur district. That combination of length and fully intra-state course makes Banas the answer.
Why the other options are wrong
- (A) Luni is associated strongly with Rajasthan, but Banas is longer within Rajasthan.
- (B) Mahi cannot be the answer because it originates in Madhya Pradesh, so it is not a river flowing entirely within Rajasthan.
- (D) Chambal is excluded because India WRIS Wiki describes it as rising near Mhow in Madhya Pradesh and then entering or forming boundaries with Rajasthan, so it is not wholly within Rajasthan.
Concept
This tests Rajasthan drainage geography, especially the distinction between rivers that merely pass through Rajasthan and rivers whose full course lies inside the state. It recurs in RAS because river origin, course and confluence facts are standard map-based prelims material.