Two flasks A and B of equal capacity of volume contain `SO_3` and CO gas respectively under similar conditions of temperature and pressure. Then, which of the following statement is true?

Options

A. A has twice the number of moles as that of B
B. B has twice the number of moles as that of A
C. A and B have equal number of moles
D. B has twice the number of atoms as that of A

Answer

To solve the problem, we need to analyze the information given about the two flasks containing different gases, SO₃ (sulfur trioxide) and CO (carbon monoxide), under the same conditions of temperature and pressure.

### Step-by-Step Solution:

1. **Identify the Gases and Their Conditions**:
- Flask A contains SO₃.
- Flask B contains CO.
- Both flasks have equal volume and are under the same temperature and pressure conditions.

2. **Apply Avogadro's Law**:
- According to Avogadro's Law, at constant temperature and pressure, equal volumes of gases contain an equal number of molecules.
- Since both flasks have the same volume, they must contain the same number of moles of gas.

3. **Determine the Number of Moles**:
- Let’s denote the number of moles of SO₃ in flask A as n₁ and the number of moles of CO in flask B as n₂.
- From Avogadro's Law, we can conclude that:
\[ n₁ = n₂ \]
- This means both flasks contain the same number of moles of gas.

4. **Analyze the Number of Atoms**:
- Now, we need to analyze the number of atoms in each gas:
- SO₃ has 1 sulfur atom and 3 oxygen atoms, totaling 4 atoms per molecule.
- CO has 1 carbon atom and 1 oxygen atom, totaling 2 atoms per molecule.
- If we assume both flasks contain the same number of moles (let's say 1 mole for simplicity), then:
- Flask A (SO₃): 1 mole × 4 atoms/molecule = 4 atoms
- Flask B (CO): 1 mole × 2 atoms/molecule = 2 atoms

5. **Conclusion**:
- Since both flasks contain the same number of moles, the correct statement is that both flasks contain equal numbers of moles of gas.
- Therefore, the correct answer is that the number of moles in flask A is equal to the number of moles in flask B.

### Final Answer:
The true statement is that both flasks A and B have equal numbers of moles of gas.