Wave Motion 3 Question 6

6. The ratio of the speed of sound in nitrogen gas to that in helium gas, at 300K is

(1999, 2M)

(a) (2/7)

(b) (1/7)

(c) (3)/5

(d) (6)/5

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Answer:

Correct Answer: 6. (c)

Solution:

  1. Speed of sound in an ideal gas is given by v=γRTM⇒∴vγM ( T is same for both the gases) vN2vHe=γN2γHeMHeMN2=7/55/3(428)=3/5

γN2=75(Diatomic)

γHe=53(Monoatomic)



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