NOTE:
The phenomenon of resonance gives identical bonding and hence identical bond lengths.

$$C - C$$  bond order in benzene = 1.5

Paper chromatography is a type of partition chromatography which is based on the principle of continuous differential partitioning of components of a mixture between stationary and mobile phases.

The electronegativity follows the order $$N < O < F.$$   So, due to electronegative character the order of $$-I$$ -effect is
$$ - N{R_2} < - OR < - F$$

$${3^ \circ }$$  carbocations are most stable.

Isomers which are possible by rotation about single bonds without cleavage of any bond are called conformers. In ethane, an infinite number of conformations are possible. There are two extreme forms, the staggered conformation, which is the most stable and the eclipsed conformation which is least stable. Among the conformers of ethane, bond angle and bond length remains same while their energy, stability and dihedral angle are different.

The order of stability of carbocations is :
$${\left( {C{H_3}} \right)_3}\mathop C\limits^ + > {\left( {C{H_3}} \right)_2}\mathop C\limits^ + H > \mathop C\limits^ + {H_3}$$

Pair of optical isomerism and geometrical isomerism are able to exhibit the phenomenon of stereoisomerism because both type of isomers differ only in their orientation in space.

In $${S_N}1$$  reaction, there is slight more inversion product than retention product because $${S_N}1$$  reaction also depend on shielding effect of the front side of the reacting carbon.

\[{{R}_{3}}COH\xrightarrow[Conc.\,HCl]{Anhy.\,ZnC{{l}_{2}}}{{R}_{3}}C.Cl\]
It is substitution reaction. \[{{R}_{3}}C.Cl\]  being insoluble in \[{{H}_{2}}O\]  give turbid solution.