Question

# 1 TORR is equal to(A) $1mm{\text{ }}of{\text{ }}Hg$(B) $10mm{\text{ }}of{\text{ }}Hg$(C) $0.5mm{\text{ }}of{\text{ }}Hg$(D) $5mm{\text{ }}of{\text{ }}Hg$

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Hint: Torr is a unit of pressure named after the scientist Evangelista Torricelli who discovered the principle of a barometer. Torr was named in the honor of the inventor of the barometer, Evangelista Torricelli. One unit of gas pressure is expressed as a millimeter of mercury (mmHg).

Torr is a unit of pressure. It is defined as exactly $1/760\;$ of a standard atmosphere. The relation between the torr and millimeter of mercury is the following:
${\text{1 Torr = 0}}{\text{.999999857533699 mm Hg}} \approx 1mm Hg$
${\text{1 mm Hg = 1}}{\text{.000000142466321 Torr}}$
1 torr is equal to the 1mm of Hg.
Hence, the correct option is (A) is correct.

The bar (denoted by the bar), defined as ${\text{100 kPa}}$ exactly.
The atmosphere (denoted by atm), defined as $101.325kPa$.
The S.I. unit of pressure is Pascal (denoted by Pa), which is equal to one Newton per square meter $\left( {{\text{N/}}{{\text{m}}^{\text{2}}}} \right)$. The pressure is a scalar quantity.