A barometer reads 75 cm of mercury. When 2.0cm $^{3}$ of air at atmospheric pressure is introduced into space above the mercury level, the volume of the space becomes 50cm $^{3}$ . The length by which the mercury column descends is

3 cm of Hg

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Solution

The correct option is A 3 cm of Hg
Let the new pressure inside be $P$ after air introduced.
For the air,
$P_{1} V_{1} = P_{2} V_{2}$
$⟹ P (50) = (75) (2)$
$⟹ P = 3 c m o f H g$

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A barometer reads 75 cm of mercury. When 2.0cm3 of air at atmospheric pressure is introduced into space above the mercury level, the volume of the space becomes 50cm3. The length by which the mercury column descends is

The correct option is A 3 cm of HgLet the new pressure inside be P after air introduced.For the air,P1V1=P2V2⟹P(50)=(75)(2)⟹P=3 cm of Hg

A barometer reads 75 cm of mercury. When 2.0cm $^{3}$ of air at atmospheric pressure is introduced into space above the mercury level, the volume of the space becomes 50cm $^{3}$ . The length by which the mercury column descends is

The correct option is A 3 cm of Hg
Let the new pressure inside be $P$ after air introduced.
For the air,
$P_{1} V_{1} = P_{2} V_{2}$
$⟹ P (50) = (75) (2)$
$⟹ P = 3 c m o f H g$