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Science Assertion (A) & Reason (B) MCQ

Gravitation · Jharkhand Board (JAC) STD 9 (Jharkhand - English Medium). 5 questions.

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Assertion (A) & Reason (B) MCQ

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5 questions · timed · auto-graded

MCQ 11 Mark
A statement of Assertion is given by the corresponding statement of Reason. Of the statements, mark the correct answer as:
Assertion: A planet is heavently body revolving around the sun.
Reason: A planet revolving around the sun follows Kepler's law.
  • A
    If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
  • ✓
    If both Assertion and Reason are true, but Reason is not the correct explanation of Assertion.
  • C
    If Assertion is true, but Reason is false.
  • D
    If Assertion is false, but Reason is true.
Answer
Correct option: B.
If both Assertion and Reason are true, but Reason is not the correct explanation of Assertion.

Kepler’s the first law states that the planet follows an ellipse, the planet is at different distances from the Sun at different parts in its orbit. So the planet has to move faster when it is closer to the Sun so that it sweeps equal areas in equal times.

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MCQ 21 Mark
A statement of Assertion is given by the corresponding statement of Reason. Of the statements, mark the correct answer as:
Assertion: At the centre of earth, the value of gravitational acceleration is maximum.
Reason: On going below the earth surface, the value of gravitational acceleration increases.
  • A
    If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
  • B
    If both Assertion and Reason are true, but Reason is not the correct explanation of Assertion.
  • C
    If Assertion is true, but Reason is false.
  • ✓
    If Assertion and Reason both are false.
Answer
Correct option: D.
If Assertion and Reason both are false.
Near Earth's surface, gravitational acceleration is approximately $9.8m/ s^2$
The earth surface, the value of gravitational acceleration increases.
Giving us acceleration due to gravity equal to $\frac{4}{3\pi\text{r}}$ (density). At the surface of the earth this value will be maximum because $'r'$ will be max. When $'r'$ becomes less (i.e when we go down in earth) this value also decreases.
Hence, acceleration due to gravity decreases with increase in depth.
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MCQ 31 Mark
In the following Question, the Assertion and Reason have been put forward. Read the statements carefully and choose the correct alternative from the following:
Assertion: Nobody can sink in the Dead Sea.
Reason: The upthrust exerted by a fluid; independent of the volume of the immersed body.
  • A
    Both the Assertion and the Reason are correct and the Reason is the correct explanation of the Assertion.
  • B
    The Assertion and the Reason are correct but the Reason is not the correct explanation of the Assertion.
  • ✓
    Assertion is true but the Reason is false.
  • D
    The statement of the Assertion is false but the Reason is true.
Answer
Correct option: C.
Assertion is true but the Reason is false.
Archimedes' principle states that the upward buoyant force that is exerted on a body immersed in a fluid, whether fully or partially submerged, is equal to the weight of the fluid that the body displaces and acts in the upward direction at the center of mass of the displaced fluid.
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MCQ 41 Mark
In the following Questions, the Assertion and Reason have been put forward. Read the statements carefully and choose the correct alternative from the following:
Assertion: Mass remains constant at every point in the universe.
Reason: Mass of a body can be zero.
  • A
    Both the Assertion and the Reason are correct and the Reason is the correct explanation of the Assertion.
  • B
    The Assertion and the Reason are correct but the Reason is not the correct explanation of the Assertion.
  • ✓
    Assertion is true but the Reason is false.
  • D
    The statement of the Assertion is false but the Reason is true.
Answer
Correct option: C.
Assertion is true but the Reason is false.
No, it is not possible for any body to have zero mass in outer space. However, it's weight can be (nearly) zero. Mass is an intrinsic property, which means it depends upon the object alone, and not upon other factors.
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MCQ 51 Mark
A statement of Assertion is given by the corresponding statement of Reason. Of the statements, mark the correct answer as: 
Assertion: To float, a body must displace liquid whose weight is greater than actual weight of the body.
Reason: During floating the body will experience no net downward force in that case.
  • A
    If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
  • B
    If both Assertion and Reason are true, but Reason is not the correct explanation of Assertion.
  • ✓
    If Assertion is true, but Reason is false.
  • D
    If Assertion is false, but Reason is true.
Answer
Correct option: C.
If Assertion is true, but Reason is false.
body is less than the density of liquid.
Net force = Actual weight
Upthrust force = Actual weight
Weight of liquid displaced. The body will rise above the surface of liquid to such an extent that the weight of the liquid displaced by the immersed part of the body (i.e. upward thrust) becomes equal to the weight of the body. Thus the body will float when upward thrust is more than its actual weight. In this special case the density of solid
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