Question

The unit torr is related to the barometric height as
A. 1torr = 1cm of Hg
B. 1torr = 0.76m of Hg
C. 1torr = 1mm of Hg
D. 1torr = 1m of Hg

Answer 1

Hint: It is really important to be able to convert a unit into some different unit. Although the SI unit of pressure is Pascal (Pa), in physics, we also use many other terms such as torr or barometric height or atm as an unit for pressure.

Complete answer:
A barometer tests the pressure of the gas at the height of the mercury column. A millimetre of mercury (mmHg) is one unit of gas pressure. In honour of the inventor of the barometer, Evangelista Torricelli, the equivalent unit of mmHg is called the torr. The normal unit of pressure is the pascal (Pa).
So, from the above statement we can conclude that the Option C is the correct answer, i.e.,
1torr = 1mm of Hg
Note: The atmosphere (atm) is another unit of pressure widely used. 1 atm of pressure is considered the normal ambient pressure which is equivalent to 760 mmHg which is 101.3 kPa. Pounds/square inch (psi) is often also specified as atmospheric pressure. The sea-level air pressure is 14.7 psi
So now,
1 atm = 760 mm of Hg = 760 torr

So, the correct answer is “Option B”.

Note:
The SI unit of pressure, Pascal (Pa) is named after famous French Mathematician and Physicist Blaise Pascal. He was also an early pioneer of “The Game Theory”
\[1\text{ }Pa\text{ }=~0.00750062\text{ }torr\text{ }=\text{ }0.00750062\text{ }mm\text{ }of\text{ }Hg\text{ }=\text{ }9.86923\times {{10}^{-6}}\]