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NEETPhysicsMechanical Properties of Fluids

Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): When a mercury barometer tube is tilted by an angle from the vertical, the length of the mercury column inside the tube increases. Reason (R): The vertical height of the mercury column remains constant as it depends only on the external atmospheric pressure and the density of mercury. In the light

Options

  1. ABoth Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
  2. BBoth Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
  3. CAssertion (A) is true but Reason (R) is false.
  4. DAssertion (A) is false but Reason (R) is true.

Correct answer

B. Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).

Step-by-step solution

The atmospheric pressure supports a vertical column of mercury of height h , given by P = g h . Since the atmospheric pressure P and the density of mercury are constant, the vertical height h of the mercury column must remain constant, regardless of the tilt of the tube. Thus, the Reason is true. When the tube is tilted by an angle from the vertical, the length of the mercury column l along the tube is related to the vertical height h by h = l . Therefore, l = h . Since 0 , the length l must be greater than h . Thu

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