Explanation:
As it is known that [tex]SF_{6}[/tex] molecule is a non-linear molecule. Therefore, its isochoric heat capacity will be as follows.
       [tex]C_{v} = \frac{3}{2}R + \frac{3}{2}R + (3 \times 7 - 6)R[/tex]
             = [tex]\frac{3}{2}R + \frac{3}{2}R + 15R[/tex]
             = 18 R
Also, Â Â [tex]C_{V} = M \times C_{v}[/tex]
where, Â Â [tex]C_{V}[/tex] = molar heat capacity
          M = molecular mass
        [tex]C_{v}[/tex] = specific heat
Hence, calculate the value of [tex]C_{v}[/tex] as follows.
         [tex]C_{V} = M \times C_{v}[/tex]
        [tex]8 \times 8.314 \times 10^{7} = 146.06 \times C_{v}[/tex]
        [tex]C_{v} = 10.2 \times 10^{6} erg. K^{-1}. gm^{-1}[/tex]
This means that value of isochoric specific heat is [tex]10.2 \times 10^{6} erg. K^{-1}. gm^{-1}[/tex].
Yes, we have to assume ideal gas behavior because for ideal gas:
             dU = [tex]nC_{v}dT[/tex]
Whereas for real gases "[tex]\frac{an^{2}}{V^{2}}[/tex]" has to be added here.
