1. 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.

2. Which is Largest railway route in India ?

Answer: Dibrugarh in Assam to Kannyakumari in Tamil Nadu.

3. Which is the lightest gas ?

Answer: Hydrogen

4. Which is the longest wall in world ?

Answer: Great wall of China

5. Which is smallest planet ?

Answer: Mercury

6. Which is Longest road tunnel in the World ?

Answer: Lærdal Tunnel (Norway - 24.51 kilometre)

7. Which is the deepest lake of the world ?

Answer: Lake Baikal