Kinetic Theory

JEE Main level, single correct, medium

151 of 168

Question 151 of 168

Number of molecules in a volume of 4cm34{cm}^{3} of a perfect monoatomic gas at some temperature T and at a pressure of 2cm2cm of mercury is close to? (Given, mean kinetic energy of a molecule (at T) is 4×10−14erg,g=980cms−24\times {10}^{-14}erg,g=980cm{s}^{-2} density of mercury =13.6gcm−3=13.6g{cm}^{-3})

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Answer: (A) 4.8×10184.8\times {10}^{18}

N=PVKTN=\dfrac{PV}{KT}
U=32KTU=\dfrac{3}{2}KT
∴N=3PV2U=3.99×1018∴N=\dfrac{3PV}{2U}=3.99\times {10}^{18}

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