In India, why is 28th February celebrated every year as National Science Day?

Introduction / Context:
National Science Day is an important observance in India aimed at promoting scientific temper, encouraging students to pursue science, and remembering a historic scientific achievement by an Indian scientist. Many competitive exams ask why this particular date, 28th February, was chosen. The answer lies in a breakthrough discovery in the field of physics that later earned a Nobel Prize.

Given Data / Assumptions:

• The date in question is 28th February, celebrated as National Science Day in India.
• We must identify the event or reason associated with this date.
• Options mention the Raman Effect, ISRO, C. V. Raman's birth anniversary, and India's first nuclear test.
• We assume basic knowledge of Indian scientific history.

Concept / Approach:
On 28th February 1928, Sir Chandrasekhara Venkata Raman, popularly known as C. V. Raman, discovered a phenomenon related to the scattering of light, later called the Raman Effect. This discovery provided evidence of the quantum nature of light and earned him the Nobel Prize in Physics in 1930. The Government of India later designated 28th February as National Science Day to honour this discovery and to celebrate science and its applications in everyday life. The date is not chosen for the founding of ISRO, for Raman's birthday, or for nuclear tests, making the Raman Effect the correct focus.

Step-by-Step Solution:
Step 1: Recall the historic scientific event on 28th February 1928: C. V. Raman's experimental observation of a special scattering of light. Step 2: Recognise that this phenomenon became known as the Raman Effect, a milestone in spectroscopy and quantum physics. Step 3: Note that the Government of India selected 28th February as National Science Day to commemorate this achievement. Step 4: Compare the options and see that only option a directly connects 28th February with the Raman Effect. Step 5: Eliminate the other options, which refer to different dates or events in Indian science and technology history.

Verification / Alternative check:
School textbooks, government notifications, and media coverage every year mention that National Science Day is observed to mark the discovery of the Raman Effect. Science exhibitions and lectures organised on this day often highlight C. V. Raman's work and discuss the importance of scientific research in India. These consistent references confirm that the day honours the Raman Effect, not the other events listed in the options.

Why Other Options Are Wrong:
The establishment of ISRO is a major milestone but does not fall on 28th February. C. V. Raman's birth anniversary falls on a different date, and so does the anniversary of India's first nuclear test (Pokhran I, conducted in May 1974). Therefore, options b, c, and d do not match the specific significance of 28th February in the Indian scientific calendar.

Common Pitfalls:
Some students confuse Raman's birthday with the date of the Raman Effect discovery or associate National Science Day with other high profile scientific achievements like space launches or nuclear tests. Reading the exact wording of the question and remembering that National Science Day is a tribute to the Raman Effect helps avoid such mistakes.

Final Answer:
28th February is celebrated as National Science Day in India to commemorate the discovery of the Raman Effect by C. V. Raman.