Amercury manometer is connected on one side to a bulb containing argon, while the other end is open to atmospheric pressure, which is 762 mmhg. the mercury level in the open end of the manometer is 22 mm below that in the side connected to the argon. what is the pressure of argon, in mmhg?

740, mm of Hg

Explanation:

The pressure of argon , in mm of Hg = difference in the level of mercury on either side of the manometer.

mercury column  in the open end of the manometer is 22 mm below that in the side connected to the argon and 762 mmHg,  end is open to atmospheric pressure.

therefore, The pressure of argon , in mm of Hg  =762 -22 = 740, mm of Hg

the answer is b, have negligible mass