Heat and Thermodynamics 4 Question 5

5. A cylinder with fixed capacity of 67.2L contains helium gas at STP. The amount of heat needed to raise the temperature of the gas by 20C is

[Take, R=8.31Jmol1K1 ]

(2019 Main, 10 April I)

(a) 700J

(b) 748J

(c) 374J

(d) 350J

Show Answer

Solution:

  1. Given, capacity of cylinder is =67.2L and ΔT=20C

At STP volume =22.4L

Number of moles =67.222.4=3

Now, change in heat is given as

ΔQ=nCVΔT

Substituting the given values, we get

ΔQ=3×3R2×20( for He gas, CV=32R)=90RJ

Given, R=8.31Jmol1K1

ΔQ=90×8.31=747.9J=748J



जेईई के लिए मॉक टेस्ट

एनसीईआरटी अध्याय वीडियो समाधान

दोहरा फलक