Choose the odd colour from the following alternatives based on the visible spectrum of light.

Introduction / Context:
This general aptitude question tests your knowledge of colours in the visible spectrum of light. Many school level science lessons describe the rainbow using the familiar pattern of seven colours. Recognizing which colours belong to this spectrum helps you solve this type of odd one out question quickly.

Given Data / Assumptions:

• The options are: Violet, Blue, Indigo, and White.
• You are asked to choose the colour that does not belong with the others based on the standard visible spectrum.
• Assume the typical VIBGYOR (Violet, Indigo, Blue, Green, Yellow, Orange, Red) ordering for rainbow colours.

Concept / Approach:
The visible spectrum consists of seven main colours often memorized by the acronym VIBGYOR. Violet, Indigo, and Blue are all part of this list. White, however, is not a single spectral colour; instead, it is a combination of all visible wavelengths. Therefore, by identifying which colours are basic spectrum components, you can find the odd one.

Step-by-Step Solution:
Step 1: Note that Violet is explicitly listed as the first colour in the VIBGYOR sequence. Step 2: Indigo is the second colour in the VIBGYOR sequence and is also a pure spectral colour. Step 3: Blue is the third colour in the visible spectrum sequence and is again a basic spectral colour. Step 4: White is not a single spectral colour. It is produced when light contains a balanced combination of all the spectral colours or when the eye perceives multiple wavelengths together. Step 5: Since the first three options are individual spectral colours and the last is a mixture, White is the odd colour.

Verification / Alternative check:
You can also think about a simple prism experiment from basic physics. When white light passes through a glass prism, it splits into seven colours: Violet, Indigo, Blue, Green, Yellow, Orange, and Red. This clearly shows that Violet, Indigo, and Blue are components of white light, while white itself is the combined result of all those wavelengths. This experiment based mental picture confirms that White is different from the three spectral colours listed.

Why Other Options Are Wrong:

• Violet: A distinct spectral colour and part of the standard VIBGYOR list, so it belongs with Indigo and Blue.
• Blue: Another major spectral colour that appears in the rainbow, so it is not odd.
• Indigo: Also one of the seven colours in the visible spectrum and similar in nature to Violet and Blue.

Common Pitfalls:
Some learners may think that Indigo is odd because it is less frequently mentioned in everyday life compared to Blue or Violet. Others may confuse the classification by thinking in terms of favourite colours rather than scientific spectrum colours. The correct reasoning must rely on the standard physics based definition of the visible spectrum, which clearly separates White from the other options.

Final Answer:
White