# If $\varepsilon_{C-C}=348kJmol^{-1},\varepsilon_{C-H}=412kJ mol^{-1}$ and $\varepsilon_{H-H}=436KJ mol^{-1}$,the pauling electronegativity of C is about (Given : electronegativity of H =2.1)

$\begin{array}{1 1}1.64\\1.82\\2.58\\2.91\end{array}$

$\Delta /kJ mol^{1}=(\varepsilon_{AB}-\sqrt{\varepsilon_{AA}\varepsilon_{BB}}/kJmol^{-1}=412-\sqrt{348\times 436}=412-\sqrt{151728}=412-389.5=22.5$
Hence $\varkappa_C-\varkappa_H=0.1018\sqrt{22.5}=0.1018\times 4.74=0.48$
$\varkappa_C=\varkappa_H+0.4=2.1+0.48=2.58$