Question

Convert 0.250 atm to mmHg

Answer 1

Both atm and mmHg are pressure units.
mmHg is millimeters mercury, in this pressure is calculated by the height of mercury level.
1 atm is equivalent to 760.0 mmHg
therefore 0.250 atm is equivalent to - 760.0 mmHg/atm x 0.250 atm 
pressure in mmHg is - 190 mmHg