The unit torr is related to the barometric height as :

Options

A. `1 "torr"=1 "cm of Hg"`
B. `1"torr"=0.76"m of Hg"`
C. `1"torr"=1"mm of Hg"`
D. `1"torr"=1"m of Hg"`

Answer

To solve the question regarding the relationship between the unit torr and barometric height, we will analyze the options provided and identify the correct relationship.

### Step-by-Step Solution:

1. **Understanding the Unit Torr**:
- The unit "torr" is a unit of pressure defined based on the height of a mercury column in a barometer.

2. **Identifying the Barometric Height**:
- Barometric height refers to the height of the mercury column in a barometer, which is used to measure atmospheric pressure.

3. **Analyzing the Options**:
- Option 1: 1 Torr = 1 centimeter of Hg
- Option 2: 1 Torr = 0.76 m of Hg
- Option 3: 1 Torr = 1 mm of Hg
- Option 4: 1 Torr = 1 meter of Hg

4. **Recalling the Definition of Torr**:
- It is known that 1 torr is defined as the pressure exerted by a 1 mm height of mercury (Hg) at standard gravity.

5. **Selecting the Correct Option**:
- Based on the definition, we can conclude that:
- 1 Torr = 1 mm of Hg.
- Therefore, the correct answer is **Option 3**.

### Final Answer:
1 Torr is equal to 1 mm of Hg.

---