The gas law relating volume with its number of molecules is called

Options

A. Boyl's law
B. Gay-Lussac's law
C. Avogadro's law
D. Ohm's law

Answer

To solve the question "The gas law relating volume with its number of molecules is called," we will analyze the options provided and identify the correct gas law.

### Step-by-Step Solution:

1. **Understand the Question**: We need to identify the gas law that relates the volume of a gas to the number of molecules (or moles) of that gas.

2. **Evaluate Boyle's Law**:
- Boyle's Law states that pressure (P) is inversely proportional to volume (V) when temperature (T) and the number of molecules (n) are constant.
- Mathematically, it is expressed as \( PV = \text{constant} \).
- This law does not relate volume to the number of molecules directly, so it is not the correct answer.

3. **Evaluate Gay-Lussac's Law**:
- Gay-Lussac's Law states that the pressure of a given mass of gas varies directly with its temperature when volume and the number of molecules are constant.
- It can be expressed as \( P/T = \text{constant} \).
- This law also does not relate volume to the number of molecules, so it is not the correct answer.

4. **Evaluate Avogadro's Law**:
- Avogadro's Law states that equal volumes of gases, at the same temperature and pressure, contain an equal number of molecules.
- Mathematically, it can be expressed as \( V \propto n \) or \( V/n = \text{constant} \).
- This law directly relates volume to the number of molecules, making it the correct answer.

5. **Evaluate Ohm's Law**:
- Ohm's Law relates to electricity and states that the current (I) through a conductor between two points is directly proportional to the voltage (V) across the two points.
- It is expressed as \( V = IR \), where R is resistance.
- This law is unrelated to gas laws and does not pertain to volume or molecules, so it is not the correct answer.

6. **Conclusion**: The gas law that relates volume with its number of molecules is **Avogadro's Law**.

### Final Answer:
The gas law relating volume with its number of molecules is called **Avogadro's Law**.