1. Which is longest river in world ?

Answer: Nile, Africa

2. Which is highest dam in world ?

Answer:

Jinping-I Dam - 305 m (1,001 ft) in China on Yalong river.
Second Highest is Nurek Dam 300 m (980 ft) Tajikistan on Vakhsh river.

3. Which is the longest rail tunnel in India ?

Answer: Pir Panjal (J&k, 11215 metre)

4. Which is largest Dam in World ?

Answer: Three Gorges (China)

5. Which state is largest by Population ?

Answer: Uttar Pradesh

6. Which is the deepest lake of the world ?

Answer: Lake Baikal

7. Which is the highest waterfall in the world ?

Answer: Angel, Venezuela