What physical quantity is measured in torr ? How is it related to the S.I. unit of the quantity ?

Answer

To solve the question, we will break it down into two parts: identifying the physical quantity measured in torr and explaining its relation to the SI unit of that quantity.

### Step 1: Identify the Physical Quantity Measured in Torr
- The physical quantity that is measured in torr is **atmospheric pressure**. Torr is a unit that quantifies the pressure exerted by the atmosphere.

### Step 2: Relate Torr to the SI Unit of Atmospheric Pressure
- The SI unit for atmospheric pressure is the **Pascal (Pa)**.
- We know from the definition that **1 Torr is equivalent to 1 mm of mercury (Hg)**.
- Additionally, it is established that **1 Torr is equal to 133.322 Pascals**.

### Summary of the Solution
1. The physical quantity measured in torr is **atmospheric pressure**.
2. The relation between torr and the SI unit (Pascal) is given by:
- **1 Torr = 133.322 Pascals**.