Unit of vapour density is

Options

A. `mol kg^(-1)`
B. `mol L^(-1)`
C. `kg m^(-3)`
D. None of these

Explanation

To determine the unit of vapor density, we can follow these steps:

### Step 1: Understand the Definition of Vapor Density
Vapor density is defined as the mass of a certain volume of gas compared to the mass of an equal volume of hydrogen at the same temperature and pressure.

### Step 2: Formula for Vapor Density
The formula for vapor density (VD) can be expressed as:
\[ VD = \frac{\text{Molar Mass}}{2} \]
where molar mass is the mass of one mole of a substance.

### Step 3: Analyze the Units
- The molar mass is typically measured in grams per mole (g/mol).
- When calculating vapor density using the formula, we divide the molar mass by 2.

### Step 4: Determine the Resulting Units
Since vapor density is derived from the molar mass divided by a constant (2), the units of vapor density can be analyzed as follows:
\[ \text{Vapor Density} = \frac{\text{g/mol}}{2} \]
However, since 2 is a dimensionless number (a pure number), the units effectively cancel out.

### Step 5: Conclusion
Thus, vapor density is considered to be unitless or dimensionless.

### Final Answer:
The unit of vapor density is unitless.

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