Correct Option
The correct option is (c) 1 and 3 only.
Explanation
The Ganga is the most important river of India, rising in the Gangotri glacier near Gaumukh in the Uttarkashi district of Uttarakhand. Its basin covers a significant portion of the northern plains, characterized by a mature stage of river development with a very gentle gradient.
Statement-wise Analysis
- Statement 1 is Correct: The total length of the river Ganga is approximately 2,525 km. It is the longest river entirely within India, flowing through the states of Uttarakhand, Uttar Pradesh, Bihar, and West Bengal before entering Bangladesh.
- Statement 2 is Incorrect: Ambala is located around the water divide between the Indus and the Ganga river systems. The plains extending from Ambala to the Sunderban (the deltaic region) stretch over a distance of approximately 1,800 km, not 500 km.
- Statement 3 is Correct: Despite the vast distance of nearly 1,800 km between Ambala and the Sunderban, the difference in elevation is minimal. Ambala is located at an elevation of approximately 300 metres above mean sea level, while the Sunderban is near sea level. Consequently, the fall in slope is hardly 300 metres. This results in a very gentle gradient of roughly 1 metre for every 6 km, which contributes to the river developing large meanders in this stretch.
Key Takeaway: The Ganga plains are characterized by an extremely gentle slope (approx. 1 metre drop per 6 km), which causes the river to flow sluggishly and form extensive meanders and ox-bow lakes in its lower course.