1 mole of an ideal gas is contained in a cubical volume V, ABCDEFGH at 300 K (figure). 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:
                               

1. the pressure on EFGH would be zero. 
2. the pressure on all the faces will be equal.
3. the pressure on EFGH would be double the pressure on ABCD.
4. the pressure on EFGH would be half that on ABCD.

(4) Hint: The pressure on a wall depends on the momentum transferred by the gas molecules.
Step 1: Find the momentum transferred by the gas molecules to the face EFGH.
In an ideal gas, when a molecule collides elastically with a wall, the momentum transferred to each molecule will be twice the magnitude of its normal momentum.
For the face EFGH, it transfers only half of that.