Gases | First Year Chemistry Past Paper MCQs | mosaicbro.com

Gases | First Year Chemistry Past Paper MCQs

7 of 29 questions (Page 4 of 5)

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22 Which of the following will have the same number of moles at S.T.P?
Correct Answer: A
Explanation: At STP, equal volumes of gases contain equal moles (Avogadro’s law). 280 cm³ = 0.28 dm³ of any gas ≈ 0.0125 moles.
23 The absolute zero is:
Correct Answer: C
Explanation: Absolute zero is theoretically unattainable; gases liquefy/solidify before reaching it.
24 Standard temperature is:
Correct Answer: A
Explanation: Standard temperature = 0°C (273.15 K) for gas measurements.
25 The color of NO₂ gas is:
Correct Answer: C
Explanation: NO₂ is a reddish-brown gas due to its absorption spectrum.
26 Pilots feel uncomfortable breathing in unpressurized cabins due to:
Correct Answer: B
Explanation: At high altitudes, low O₂ partial pressure causes hypoxia.
27 Plasmas are found in everything from the sun to:
Correct Answer: D
Explanation: Plasmas (ionized matter) exist in stars (sun) and even fundamental particles (quarks).
28 Which gas will diffuse more rapidly among the following?
Correct Answer: B
Explanation: H₂ (2 g/mol) has the lowest molar mass, diffusing fastest (Graham’s law).
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