Loschmidt number is the number of -

Options

A. Atoms present in 1 gram mole of a gas at STP
B. Atoms present in 1 mL of a gas at STP
C. Molecules present in 1 gram mole of a gas at STP
D. Molecules present in 1 mL of a gas at STP

Answer

**Step-by-Step Solution:**

1. **Understanding the Loschmidt Number**: The Loschmidt number is defined as the number of molecules in a given volume of gas at standard temperature and pressure (STP).

2. **Standard Conditions**: Standard temperature and pressure (STP) is typically defined as a temperature of 0 degrees Celsius (273.15 K) and a pressure of 1 atmosphere (atm).

3. **Volume Consideration**: The volume we consider for the Loschmidt number is 1 cm³ (or 1 mL) of gas.

4. **Calculation of the Loschmidt Number**: At STP, the approximate value of the Loschmidt number is 2.68 x 10²⁵ molecules/m³. However, when considering the number of molecules in 1 cm³, we can express it as approximately 2.68 x 10¹⁹ molecules.

5. **Conclusion**: Therefore, the Loschmidt number is the number of molecules present in 1 cm³ (or 1 mL) of gas at standard temperature and pressure.

**Final Answer**: The Loschmidt number is the number of molecules present in 1 mL of a gas at standard temperature and pressure.

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