1. Which is the longest wall in world ?

Answer: Great wall of China

2. Which is Largest library in the world ?

Answer: United State Library of Congress, Washington D.C.

3. Which is Place of heaviest rainfall ?

Answer: Mausinram (Meghalaya)

4. Which is Longest Dam in India ?

Answer: Hirakod Dam (Orissa)

5. Which is longest river in world ?

Answer: Nile, Africa

6. Which is largest Dam in World ?

Answer: Three Gorges (China)

7. 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.