1. Which is Largest library in the world ?

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

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 smallest planet ?

Answer: Mercury

4. Which is the longest River in the World ?

Answer: Nile

5. Which is smallest continent of world ?

Answer: Australia

6. Which is Place of heaviest rainfall ?

Answer: Mausinram (Meghalaya)

7. Which is the lightest gas ?

Answer: Hydrogen