\\\\(T_c=\\\\) Temperature at and above which the vapour state can not be further liquified. \\\\(P_c=\\\\) Pressure of gas in its critical state\\\\(V_c=\\\\) Volume of gas in its critical state. relation with the van der waals constants -\\\\(T_c = 8a / 27 Rb\\\\) So \\\\(a=27T_cRb/8\\\\)\\\\(V_c = 3b\\\\) So \\\\(b=V_c/3\\\\) \\\\(P_c = a / 27 b^2\\\\) ....(1)put the value of a and b in equation (1)\\\\(P_c = \\dfrac{27T_c\ imes R\ imes b}{8\ imes 27\ imes b^2}\\\\)\\\\(P_c = \\dfrac{27T_c.R}{8\ imes 27\ imes b}= \\dfrac{27T_c.R}{8\ imes 27\ imes V_c/3}\\\\)\\\\(P_cV_c = \\dfrac{3}{8}RT_c\\\\)