Identify the incorrect statement — Choose the one option below that is NOT correct.
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AThe heat capacity of a diatomic gas is higher than that of a monoatomic gas at the same conditions
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BEqual volumes of argon and krypton at the same T and P contain equal numbers of atoms
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CA volume of 22.4 L of hydrogen gas (H₂) at NTP contains 6.023 × 10^23 hydrogen atoms
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DA binary mixture that boils with the same composition in vapor and liquid phases at a given pressure is called an azeotrope
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ENone of the above
Answer
Correct Answer: A volume of 22.4 L of hydrogen gas (H₂) at NTP contains 6.023 × 10^23 hydrogen atoms
Explanation
Introduction:This mixed-concepts question probes knowledge of specific heats, Avogadro’s law, molar volume at standard conditions, and the definition of an azeotrope. Only one statement is intentionally incorrect.
Given Data / Assumptions:
- NTP molar volume ≈ 22.4 L per mole of an ideal gas.
- Hydrogen is diatomic (H₂) under standard conditions.
- Azeotrope: vapor and liquid have the same composition at the boiling point for a given pressure.
Concept / Approach:At NTP, 22.4 L of any ideal gas contains 1 mole of molecules, i.e., 6.023 × 10^23 molecules. For H₂, that corresponds to 2 × 6.023 × 10^23 atoms. Therefore, saying 22.4 L of H₂ contains 6.023 × 10^23 atoms is incorrect; it contains that number of molecules, not atoms.
Step-by-Step Solution:Use Avogadro’s law: equal volumes at same T, P have equal number of molecules.Compute for hydrogen: 22.4 L → 1 mol molecules → 6.023 × 10^23 molecules.Atoms present = 2 per molecule → 1.2046 × 10^24 atoms, not 6.023 × 10^23.
Verification / Alternative check:Check standard molar volume tables: 22.414 L at 0°C and 1 atm equals 1 mol of gas; terminology distinguishes molecules vs. atoms for diatomic gases.
Why Other Options Are Wrong or Right:
- (a) True: extra rotational/vibrational degrees raise heat capacity for diatomic gases.
- (b) True by Avogadro’s law when T and P are equal.
- (d) True definition of an azeotrope.
- (e) False because one incorrect statement exists, namely (c).
Common Pitfalls:Confusing “molecules” and “atoms” for diatomic gases; minor variations of standard molar volume do not change the conclusion.
Final Answer:A volume of 22.4 L of hydrogen gas (H₂) at NTP contains 6.023 × 10^23 hydrogen atoms