# 1 mole of an ideal gas is contained in a cubical volume V, ABCDEFGH at 300 K (Fig. 13.1). One face of the cube (EFGH) is

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1 mole of an ideal gas is contained in a cubical volume V, ABCDEFGH at 300 K (Fig. 13.1). One face of the cube (EFGH) is made up of a material which totally absorbs any gas molecule incident on it. At any given time,

(a) the pressure on EFGH would be zero.

(b) the pressure on all the faces will the equal.

(c) the pressure of EFGH would be double the pressure on ABCD.

(d) the pressure on EFGH would be half that on ABCD.

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(d)  The pressure on EFGH would be half that on ABCD.Comment for discussion: In the ideal case that we normally consider, each collision transfers twice the magnitude of its normal momentum. On the face EFGH, it transfers only half of that.

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Sorry, couldn't understand clearly!
Thank you
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Answer: (d) The pressure on EFGHEFGH would be half that on ABCDABCD.

The pressure on face EFGH would be half that on face ABCD. This is because force EFGH absorbs totally all the molecules incident on it. These molecules do not rebound. Change in momentum causing force and hence pressure is reduced to half compared to force/pressure on face ABCD from where molecules rebound with an equal velocity.