Convert the pressure 0.840 atm to mm hg

The pressure unit is Pascal (sign Pa) or Newton per square meter (N / m2). In addition to Pascal, a pressure measurement unit can be used bar (1 bar = 105 Pa). The old pressure units are: technical atmosphere, the symbol at (1 at = 98 066.5 Pa); standard, normal or physical atmosphere, atm (1 atm = 101 325 Pa); millimetres of mercury, the symbol mmHg, or torr (1 mmHg = 1 torr = 133,322 Pa); millimeter of water, symbol mmH2O (1 mmH2O = 9.806 65 Pa).

1 atm = 101 325 Pa
1 mmHg = 133,322 Pa

1 atm = 101 325/133.322 = 760 mmHg

0.84 atm = 760 x 0.84 = 638.4 mmHg

The correct answer is b