1. Which is Largest library in the world ?

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

2. Which is smallest state by area of India ?

Answer: Goa

3. Which is the shortest day in the year ?

Answer: December 22

4. 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.

5. Which is the lightest metal ?

Answer: Lithium

6. Which is the longest wall in world ?

Answer: Great wall of China

7. Which is the largest Mosque in World ?

Answer: Masjid al Haram (Saudi Arabia)