Explanation:

National Technology Day is celebrated on May 11 every year to commemorate the achievements of scientists, researchers, engineers and all others involved in the field of science and technology. 
The day was first observed on May 11, 1999. The day was chosen because on this day India successfully broke into the elite group of countries with nuclear weapons. On 11 May 1998, India successfully conducted three nuclear tests at Indian Army’s Pokhran Test Range in Rajasthan.