Verified Solution • 2025–26 Session moderate

QJEEM17Phb7a9: JEE Main 2017 Physics - Class 11 JEEM17Phb7a9 Solution: C P and C v are specific heats at constant pressure and…

CP and Cv are specific heats at constant pressure and constant volume respectively. It is observed that
CP – Cv = a for hydrogen gas
CP – Cv = b for nitrogen gas
The correct relation between a and b is

Multiple Choice Options

  • A a = 28 b
  • B a = 1/14 b
  • C a = b
  • D a = 14 b

Step-by-Step Verified Solution

As we know, for 1 g mole of a gas,

Cp – Cv = R where Cp and Cv are molar specific heat capacities.

So, when n gram moles are given,

Cp – Cv = Rn{R \over n}

For hydrogen (n = 2), Cp – Cv = R2{R \over 2} = aa

For nitrogen (n = 28), Cp – Cv = R28{R \over 28} = bb

∴\therefore ab=14{a \over b} = 14

⇒\Rightarrow aa = 14 bb

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