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A rigid triangular molecule consists of three non-collinear atoms joined by rigid rods. The constant pressure molar specific heat $$C_p$$ of an ideal gas consisting of such molecules is

(a) $$6R$$

(b) $$5R$$

(c) $$4R$$

(d) $$3R$$

Degrees of freedom are the number of independent parameters that define its configuration
If $$N$$ be the number of particles in a system and $$k$$ be the number of constraints between the number of degrees of freedom is given by $$f=3N-k$$ $$f=(3*3)-3$$ $$=6$$
Relation between $$f$$ and $$C_p$$ $$C_p=(f/2+1)R$$ $$\Rightarrow C_p=(6/2+1)R$$ $$C_p=4R$$