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Science Assertion - Reasoning [Phy-1 M]

Human Eye and Colourful World · CBSE STD 10 (CBSE - English Medium). 13 questions.

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Assertion - Reasoning [Phy-1 M]

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13 questions · timed · auto-graded

Question 11 Mark
In the following questions, a statement of Assertion is given by the corresponding statement of Reason. Of the statements, mark the correct answer as:
  1. If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
  2. If both Assertion and Reason are true, but Reason is not the correct explanation of Assertion.
  3. If Assertion is true, but Reason is false.
  4. If Assertion is false, but Reason is true.
  5. If Assertion and Reason both are false.
Assertion: Red light has the maximum wavelength and violet light has the minimum wavelength.
Reason: Red light deviates least, while violet light deviates maximum.
Answer
  1. If both Assertion and Reason are true and Reason is the correct explanation of Assertion.

Explanation:

his is because Violet has the least velocity in the spectrum and therefore undergoes maximum refraction. Red deviates the least as it has the highest velocity. Violet light has a shorter wavelength, and short wavelengths travel more slowly through a medium than longer ones do.

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Question 21 Mark
In the following questions, a statement of Assertion is given by the corresponding statement of Reason. Of the statements, mark the correct answer as:
  1. If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
  2. If both Assertion and Reason are true, but Reason is not the correct explanation of Assertion.
  3. If Assertion is true, but Reason is false.
  4. If Assertion is false, but Reason is true.
  5. If Assertion and Reason both are false.
Assertion: Rainbow is an example of the dispersion of sunlight by the water droplets.
Reason: Light of shorter wavelength is scattered much more than light of larger wavelength.
Answer
  1. If both Assertion and Reason are true, but Reason is not the correct explanation of Assertion.

Explanation:

Rainbow forms when sunlight hits the water droplets suspended in the atmosphere and undergoes total internal reflection. When the sunlight comes out of the drop it disperses, where the drop acts like a small prism. Hence, rainbow is an example of dispersion of sunlight.

Particles or molecules, much smaller than the wavelength of light(0.5micro metre), produce a Scattering of sunlight that is inversely proportional to the fourth power of the wavelength. This means shorter wavelength scattered much more than longer wavelength.

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Question 31 Mark
In the following questions, a statement of Assertion is given by the corresponding statement of Reason. Of the statements, mark the correct answer as:
  1. If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
  2. If both Assertion and Reason are true, but Reason is not the correct explanation of Assertion.
  3. If Assertion is true, but Reason is false.
  4. If Assertion is false, but Reason is true.
  5. If Assertion and Reason both are false.
Assertion: An image formed on retina is real. diminished and inverted in nature.
Reason: The eye lens is convex lens.
Answer
  1. If both Assertion and Reason are true, but Reason is not the correct explanation of Assertion.

Explanation:

It can be seen that the image is formed by actual light rays and thus can form a visible image on a screen placed at the position of the image. Producing a real image. Each region of the detector or retina indicates the light produced by a corresponding region of the object.

The lens is a transparent, convex lens in the eye that, along with the cornea, helps to refract light to be focused on the retina. Hence, Convex lens is present in human eye.

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Question 41 Mark
For two statements are given-one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below:
  1. Both A and R are true, and R is correct explanation of the assertion.
  2. Both A and R are true, but R is not the correct explanation of the assertion.
  3. A is true, but R is false.
  4. A is false, but R is true.
Assertion: The rainbow is seen when the sun is behind the observer.
Reason: Rainbow is produced due to dispersion of white light by small rain drops hanging in the air after the rain.
Answer
  1. Both A and Rare true, but R is not the correct explanation of the assertion.

Explanation:

Just after the rain, a large number of small droplets of water remain suspended in the air. Each drop acts like a small prism. When sunlight falls on these drops, the white light splits into seven colours. The dispersed light from a large number of drops forms a continuous band of seven colours.

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Question 51 Mark
For two statements are given-one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below:
  1. Both A and R are true, and R is correct explanation of the assertion.
  2. Both A and R are true, but R is not the correct explanation of the assertion.
  3. A is true, but R is false.
  4. A is false, but R is true.
Assertion: The twinkling of stars is due to the fact that refractive index of the earth's atmosphere fluctuates.
Reason: When light propagates from one medium to another its direction of propagation changes.
Answer
  1. Both A and Rare true, and R is correct explanation of the assertion.

Explanation:

The continuously changing atmosphere is able to cause variation in the light coming from a point-sized star because of which the star appears to be twinkling.

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Question 61 Mark
For two statements are given-one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below:
  1. Both A and R are true, and R is correct explanation of the assertion.
  2. Both A and R are true, but R is not the correct explanation of the assertion.
  3. A is true, but R is false.
  4. A is false, but R is true.
Assertion: The scattering of longer wavelengths of light increases as the size of the particles increases.
Reason: Large particles scatter lights of all wavelengths equally well.
Answer
  1. Both A and Rare true, but R is not the correct explanation of the assertion.
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Question 71 Mark
For two statements are given-one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below:
  1. Both A and R are true, and R is correct explanation of the assertion.
  2. Both A and R are true, but R is not the correct explanation of the assertion.
  3. A is true, but R is false.
  4. A is false, but R is true.
Assertion: The light of violet colour deviates the most and the light of red colour the least, while passing through a prism.
Reason: For a prism material, refractive index is highest for red light and lowest for the violet light.
Answer
  1. A is true, but R is false.

Explanation:

For a prism material refractive index is highest for violet light and lowest for the red light.

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Question 81 Mark
For two statements are given-one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below:
  1. Both A and R are true, and R is correct explanation of the assertion.
  2. Both A and R are true, but R is not the correct explanation of the assertion.
  3. A is true, but R is false.
  4. A is false, but R is true.
Assertion: Rainbow is an example of the dispersion of sunlight by the water droplets.
Reason: Light of shorter wavelength is scattered much more than light of larger wavelength.
Answer
  1. Both A and Rare true, but R is not the correct explanation of the assertion.

Explanation:

The rainbow is an arch of seven colours visible in the sky which is produced by the dispersion of sun's light by raindrops in the atmosphere

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Question 91 Mark
For two statements are given-one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below:
  1. Both A and R are true, and R is correct explanation of the assertion.
  2. Both A and R are true, but R is not the correct explanation of the assertion.
  3. A is true, but R is false.
  4. A is false, but R is true.
Assertion: Higher the refractive index of the prism material, lower is the angle of deviation.
Reason: The angle of deviation is directly proportional to the angle of prism.
Answer
  1. A is false, but R is true.

Explanation:

Higher the refractive index of the prism material, greater is the angle of deviation.

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Question 101 Mark
For two statements are given-one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below:

  1. Both A and R are true, and R is correct explanation of the assertion.
  2. Both A and R are true, but R is not the correct explanation of the assertion.
  3. A is true, but R is false.
  4. A is false, but R is true.

Assertion: The scattered light makes path of light visible.

Reason: Scattering of light is the result of Tyndall effect.

Answer
  1. Both A and Rare true, but R is not the correct explanation of the assertion.
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Question 111 Mark
For two statements are given-one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below:

  1. Both A and R are true, and R is correct explanation of the assertion.
  2. Both A and R are true, but R is not the correct explanation of the assertion.
  3. A is true, but R is false.
  4. A is false, but R is true.

Assertion: There is no dispersion of light refracted through a rectangular glass slab.

Reason: Dispersion of light is the phenomenon of splitting of a beam of white light into its constituents colours.

Answer
  1. Both A and Rare true, but R is not the correct explanation of the assertion.

Explanation:

After refraction at two parallel faces of a glass slab, a ray of light emerges in a direction parallel to the direction of incidence of white light on the slab. As rays of all colours emerge in same direction, hence there is no dispersion only lateral displacement takes place.

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Question 121 Mark
For two statements are given-one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below:

  1. Both A and R are true, and R is correct explanation of the assertion.
  2. Both A and R are true, but R is not the correct explanation of the assertion.
  3. A is true, but R is false.
  4. A is false, but R is true.

Assertion: Danger signals are red.

Reason: Red colour has smallest wavelength.

Answer
  1. A is true, but R is false.

Explanation:

Red colour has longest wavelength.

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Question 131 Mark
For two statements are given-one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below:

  1. Both A and R are true, and R is correct explanation of the assertion.
  2. Both A and R are true, but R is not the correct explanation of the assertion.
  3. A is true, but R is false.
  4. A is false, but R is true.

Assertion: A beam of white light gives a spectrum on passing through a hollow prism.

Reason: Speed of light outside the prism is different as the speed of light inside the prism.

Answer
  1. A is false, but R is true.

Explanation:

Dispersion of light cannot occur on passing through air contained in a hollow prism. Dispersion takes place because the refractive index of medium for different colours is different.

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