1. Which is smallest continent of world ?

Answer: Australia

2. Which is largest continent ?

Answer: Asia

3. Which is longest river of India

Answer: Ganges

4. Which is the lightest gas ?

Answer: Hydrogen

5. 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.

6. Which is Longest Dam in India ?

Answer: Hirakod Dam (Orissa)

7. Which is Biggest ocean in the world ?

Answer: Pacific ocean