The correct option is C 1<x≤1.4
Molar Specific heat of a gas during a polytropic process is given by (C)=CV+R1−x ..........(1)
Where x is the exponent of polytropic process which can take values in the range of (−∞<x<+∞)
Since, CO2 is a linear triatomic molecule, at normal temperatures we can say that CV=5R2
Thus, from (1) we get,
5R2≤Rx−1 ⇒52≤1x−1For x>1 ⇒x−1≤25⇒x≤1.4
∴ For values of x between 1<x≤1.4 heat capacity of gas becomes non-positive.
Thus, option (c) is the correct answer.
we know that,
Heat capacity of a gas can be negative if 1<x<γ
we can say that, Heat capacity of a gas can be non-positive iff 1<x≤γ
For CO2 we know that, γ=75=1.4
∴ we can conclude that 1<x≤1.4
Hence, option (c) is the correct answer.