Question

The table shown below gives the bond dissociation energies $\left(E_{dis}\right)$ for single covalent bonds of carbon $\left(C\right)$ atoms with element ${}^{\prime }{A}^{\prime },{}^{\prime }{B}^{\prime },{}^{\prime }{C}^{\prime }$ and ${}^{\prime }{D}^{\prime }$. Which element has the smallest size?

$\begin{array}{cc}\text{Bond}& E_{dis}\left({\text{kJ mol}}^{-1}\right)\\ C-A& 240\\ C-B& 328\\ C-C& 276\\ C-D& 485\end{array}$

• A. $A$
• B. $B$
• C. $C$
• D. $D$

Answer 1

The correct option is D $D$

From the table, we can see that $C-D$ bond has the highest bond dissociation energy of $485{\text{kJ mol}}^{-1}$. Hence, it is most difficult to break. The strength of the bond depends on the bond length. The bond length depends on the size of the atoms involved. Smaller the bonding atoms, smaller the bond length, stronger is the bond and so, higher the bond dissociation energy. The $C-D$ bond has the greatest bond dissociation energy and hence it must have smallest bond length among the four and hence, $D$ must be smallest atom among the four.