Rainbow Colors Order Online Test (General Knowledge) Updated

The rainbow is one of nature’s most beautiful and scientifically fascinating phenomena, and questions about its colours, order, formation, and related optical science are a regular feature in Pakistan’s most competitive examinations, including CSS (Central Superior Services), PMS (Provincial Management Services), NTS (National Testing Service), PPSC (Punjab Public Service Commission), FPSC (Federal Public Service Commission), SPSC, and KPPSC. Questions on rainbows appear in General Science, General Knowledge, and Current Affairs sections, covering facts such as the correct order of colours in a rainbow, the physics of light dispersion and refraction, the role of water droplets, the difference between primary and secondary rainbows, famous scientists who explained the rainbow, the mnemonic ROYGBIV, wavelengths of visible light, and rare rainbow types. A firm grasp of this topic ensures easy marks in the science section of any competitive exam. This specially curated MCQ set for GoTest.com.pk covers every important angle — the order of colours, scientific explanations, wavelength rankings, historical discoveries, types of rainbows, and fun facts about this natural wonder. Each question is followed by a detailed explanation to help you understand not just the correct answer but also the broader context. Students are strongly advised to read every explanation carefully even after getting the right answer, as exam papers often twist familiar facts. Consistent practice with these MCQs will sharpen your recall and improve your confidence for exam day.

Rainbow Colors Order Online Test (General Knowledge) Updated

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1. What physical phenomenon causes a rainbow to form?

Absorption of sunlight by moisture in the air

Refraction, reflection, and dispersion of sunlight through water droplets

Reflection of sunlight off cloud surfaces

Diffraction of sunlight around clouds

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2. At what time of day is a rainbow most likely to be visible?

At midday when the Sun is highest

At night during a full Moon

Only during overcast conditions with no direct sunlight

In the early morning or late afternoon when the Sun is low on the horizon

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3. Which scientist is credited with explaining the formation of the rainbow using a prism and the dispersion of white light?

Isaac Newton

Rene Descartes

Galileo Galilei

Albert Einstein

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4. What colours are produced when red and blue light are combined?

Magenta (pink)

Yellow

Green

Cyan

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5. How many colours are there in a rainbow?

7

5

6

8

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6. What is a "fire rainbow" or "circumhorizontal arc"?

A rainbow produced by the light of a volcanic eruption

A rainbow caused by wildfires reflecting light through smoke

A rare optical phenomenon forming a colourful horizontal arc in ice-crystal clouds

A rainbow seen only in desert regions during extreme heat

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7. What is "dispersion" of light in the context of rainbows?

The spreading of light across a large area

The reflection of light off a flat water surface

The absorption of certain colours of light by water

The separation of white light into its component colours due to different wavelengths bending by different amounts

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8. Can a rainbow ever form a complete circle?

Yes — but only during a lunar rainbow at night

No — rainbows are always semicircles

No — the physics of light prevent circular formation

Yes — a full circular rainbow can be seen from an aircraft or high elevation when conditions are right

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9. What is a "glory" in atmospheric optics, related to rainbow phenomena?

The brightest point at the top of a rainbow arc

A small, circular, rainbow-like ring of colours seen around the shadow of the observer's head on clouds or fog below

A bright halo around the full Moon

Another name for a double rainbow

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10. What is the colour order in a rainbow produced by a prism?

Differs from a natural rainbow — prisms show only three colours

Reversed compared to a natural rainbow — Violet at top, Red at bottom

Prisms produce white light, not a spectrum

Same as a natural rainbow — Red, Orange, Yellow, Green, Blue, Indigo, Violet

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11. Why does indigo appear as a separate colour in the traditional rainbow listing despite being difficult for many people to distinguish from blue and violet?

Because indigo refracts at a uniquely different angle from blue and violet

Because it has a unique chemical composition different from blue

Because it was discovered as a separate colour after the other six

Because Isaac Newton chose to include it to make the total seven colours, matching the number of musical notes and days of the week

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12. What is the speed of light in water compared to its speed in air?

Faster in water than in air

The same in both water and air

Depends on the colour of light — some faster, some slower

Slower in water than in air

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13. What is a "secondary rainbow" and how does it differ from a primary rainbow?

A rainbow that appears only at night

A smaller rainbow that appears inside the primary rainbow with the same colour order

A second rainbow of identical appearance that forms simultaneously with the primary

A larger, fainter rainbow outside the primary rainbow with the colour order reversed

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14. What are the three primary colours of light (additive colour model)?

Red, Green, Blue

Red, Yellow, Blue

Cyan, Magenta, Yellow

Orange, Green, Violet

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15. What is a "double rainbow" and what is special about it?

Two rainbows side by side at the same angle

A primary and secondary rainbow appearing simultaneously, with the secondary showing reversed colours

A rainbow reflected in a lake creating the illusion of two rainbows

A rainbow with double the number of colours

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16. What is an "infrared rainbow"?

A rainbow created by infrared heaters used in industry

A rainbow visible only with special goggles

A rainbow formed by infrared radiation just beyond the red end of the visible spectrum, detectable only by infrared cameras

A rainbow that appears only in very hot desert climates

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17. In which direction should you look to see a rainbow in the morning?

East (toward the rising Sun)

West (away from the rising Sun)

South

North

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18. What is the correct order of colours in a secondary rainbow from top to bottom?

Green, Blue, Indigo, Violet, Red, Orange, Yellow

Red, Orange, Yellow, Green, Blue, Indigo, Violet

Orange, Red, Violet, Indigo, Blue, Green, Yellow

Violet, Indigo, Blue, Green, Yellow, Orange, Red

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19. Which colour appears at the top (outermost arc) of a primary rainbow?

Blue

Violet

Yellow

Red

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20. Which colour of light has the longest wavelength in the visible spectrum?

Blue

Green

Red

Violet

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21. What is "refraction" of light?

The bending of light as it passes from one medium to another of different density

The bouncing of light off a surface

The absorption of light by a coloured surface

The scattering of light in all directions

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22. What is the phenomenon where a rainbow appears to move as you move toward it?

The rainbow reflects off moving rain clouds

Rainbow displacement

Atmospheric refraction shifting the rainbow's position

The rainbow always remains at a fixed angular distance from the observer's anti-solar point, so it appears to move with the observer

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23. What happens to light when it is "totally internally reflected" inside a raindrop?

The light passes straight through without bending

The light is completely absorbed by the water

The light is converted into heat energy

The light reflects off the inside surface of the raindrop without escaping, directing it back out through the front of the droplet

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24. In which of Newton's famous experiments did he demonstrate that white light is composed of all colours?

The apple falling experiment

The telescope experiment

The gravity well experiment

The prism experiment — passing sunlight through a glass prism in a darkened room

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25. What is the correct order of colours in a rainbow from top to bottom?

Red, Orange, Yellow, Green, Blue, Indigo, Violet

Violet, Indigo, Blue, Green, Yellow, Orange, Red

Red, Yellow, Orange, Green, Blue, Violet, Indigo

Blue, Green, Yellow, Orange, Red, Indigo, Violet

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26. Which colour appears at the bottom (innermost arc) of a primary rainbow?

Indigo

Violet

Red

Orange

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27. What is the "refractive index" of water and why is it important in rainbow formation?

Approximately 1.33 — meaning light bends as it enters water, enabling dispersion

1.0 — same as air, meaning no bending occurs

It varies with rainfall intensity and is not fixed

Approximately 2.5 — causing very strong bending

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28. Which colour of the rainbow is associated with a wavelength of approximately 580 nanometres?

Orange

Green

Yellow

Blue

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29. What is a "twinned rainbow"?

A single rainbow that splits into two arcs from a common base

Two separate rainbows that cross each other

A primary and secondary rainbow of equal brightness

A rainbow and its reflection in water appearing as twins

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30. What is the correct order of colours in a rainbow from the innermost to the outermost arc?

Blue, Green, Yellow, Orange, Red, Indigo, Violet

Violet, Indigo, Blue, Green, Yellow, Orange, Red

Red, Orange, Yellow, Green, Blue, Indigo, Violet

Green, Blue, Indigo, Violet, Red, Orange, Yellow

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31. What causes the sky inside a primary rainbow (below the arc) to appear brighter?

The rainbow itself emitting light downward

Direct sunlight reflecting off raindrops toward the observer

Light from raindrops inside the primary rainbow arc being reflected back toward the observer at multiple angles

The ground reflecting sunlight back into the sky

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32. What is "VIBGYOR" and when is it used?

The reverse mnemonic for rainbow colours from bottom to top — Violet, Indigo, Blue, Green, Yellow, Orange, Red

An alternative name for the secondary rainbow

A formula for calculating rainbow angles

A type of spectrometer used to study rainbow colours

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33. How does the size of raindrops affect the appearance of a rainbow?

Larger raindrops produce fainter rainbows; smaller drops produce brighter ones

Only medium-sized droplets can produce rainbows at all

Larger raindrops produce brighter, more vivid rainbows with well-defined colour bands; very small droplets produce white or pale fogbows

Raindrop size has no effect on rainbow appearance

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34. What is the name of the book in which Isaac Newton presented his theory of light and colours including his work on the spectrum?

The Colour of Light

Opticks

Discourse on Method

Principia Mathematica

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35. What is a "rainbow" in simple scientific terms?

A permanent atmospheric feature visible after every rainfall

A stream of pure white light reflected off rain clouds

A meteorological and optical phenomenon producing a spectrum of light in the sky caused by sunlight interacting with water droplets

A reflection of sunlight off a wet ground surface

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36. Which colour of light has the shortest wavelength in the visible spectrum?

Blue

Green

Violet

Red

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37. What is the "visible spectrum" of light?

All electromagnetic radiation including X-rays and radio waves

The colours visible only in a rainbow

The light visible only through a spectrometer

The range of electromagnetic wavelengths (approximately 380-750 nm) that the human eye can detect as colour

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38. Which colour of the rainbow has the highest frequency?

Red

Green

Orange

Violet

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39. What is the popular mnemonic used to remember the order of colours in a rainbow?

GYBIVRO

BVIGYOR

ROYGBIV

VIBGYOR

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40. What is a "fogbow"?

Another name for a secondary rainbow

A rainbow formed by artificial fog machines

A rainbow that appears in fog rather than rain, usually appearing white or very faint

A rainbow seen only in coastal foggy areas

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41. Which colour of the rainbow has the lowest frequency?

Red

Green

Violet

Blue

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42. What is the colour of the sky between the primary and secondary rainbow called?

Rainbow shadow

Descartes' Band

The neutral zone

Alexander's Dark Band

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43. What is "Roy G. Biv"?

A mnemonic device personifying the colours of the rainbow: Red, Orange, Yellow, Green, Blue, Indigo, Violet

The name of the scientist who discovered the rainbow spectrum

A type of spectrometer used to study rainbow colours

A unit of measurement for light wavelength

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44. What is a "rainbow" in folklore and cultural symbolism?

A warning sign for sailors of dangerous storms

A symbol of the four seasons of the year

A sign of forthcoming heavy rainfall

A symbol of hope, promise, good fortune, and the bridge between earth and the divine in many cultures

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45. What are "supernumerary rainbows"?

Rainbows that appear above the primary arc

Faint additional arcs of colour that appear just inside the primary rainbow

Rainbows visible only through binoculars

Rainbows with more than seven colours

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46. Which scientist first mathematically explained the geometry of rainbow formation?

Isaac Newton

Aristotle

Rene Descartes

Snell

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47. What is "white light" and how is it related to rainbow colours?

White light is a mixture of all colours of the visible spectrum combined together

White light is pure light with no colour component

White light is light that has had all colours removed

White light only contains red, green, and blue

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48. Why can two people standing side by side never see exactly the same rainbow?

Because their eyes have different sensitivities to colour

Because each observer sees light reflected from different sets of raindrops at their own specific anti-solar point

Because rainbows form at different distances for each observer

Because one person may be taller, changing the angle

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49. What is a "lunar rainbow" (moonbow)?

A rainbow that only appears during a solar eclipse

A rainbow visible only through a telescope

A rainbow formed by moonlight instead of sunlight, usually appearing white or faint

A rainbow that appears on the Moon's surface

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50. Why does a rainbow appear as an arc rather than a full line or irregular shape?

Because the Earth's curvature bends the light into an arc

Because all raindrops that send the correct wavelength of light to the observer's eye lie on a cone of approximately 42 degrees centred on the anti-solar point

Because clouds are curved

Because raindrops only form in curved patterns in the atmosphere

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51. What are the three primary colours of pigment (subtractive colour model)?

White, Grey, Black

Red, Yellow, Blue (traditional art) or Cyan, Magenta, Yellow (printing)

Orange, Green, Violet

Red, Green, Blue

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52. What is the approximate wavelength of green light in the visible spectrum?

450-495 nm

380-450 nm

620-750 nm

495-570 nm

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53. What is the role of the "anti-solar point" in rainbow formation?

The point directly opposite the Sun from the observer's position — the centre of the rainbow circle

The position of the Moon during a lunar rainbow

The point where the rainbow touches the ground

The point in the sky where sunlight is completely blocked

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54. Why is a rainbow always seen in the direction opposite the Sun?

Because rainbows are formed by light reflecting inside raindrops and returning toward the light source — back toward the observer facing away from the Sun

Because raindrops only form on the shadowed side of the sky

Because clouds block sunlight from the same direction as the Sun

Because the atmosphere bends all light to the opposite side of the sky

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55. What is "Alexander's Band" in the context of rainbows?

The colourless band at the very centre of a rainbow

The dark region of sky between the primary and secondary rainbow

A band of extra-bright light at the top of a rainbow

A rainbow that appears as a straight horizontal band

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56. What is the approximate angle of a primary rainbow as seen from the observer?

60-65 degrees from the anti-solar point

40-42 degrees from the anti-solar point

50-55 degrees from the anti-solar point

20-25 degrees from the anti-solar point

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