1. Which is the longest wall in world ?

Answer: Great wall of China

2. Which is Longest Dam in India ?

Answer: Hirakod Dam (Orissa)

3. 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.

4. Which is Longest national highway of India ?

Answer: NH-7 ( Varanasi to Kanyakumari - 2,369 km)

5. Which is tallest statue in world ?

Answer:

Spring Temple Buddha located in the Zhaocun township of Lushan County, Henan, China

6. Which is largest Dam in World ?

Answer: Three Gorges (China)

7. Which is the deepest lake of the world ?

Answer: Lake Baikal