Answer:
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