- AElectrophilic substitution reactions
- BNucleophilic substitution reactions
- ✓Electrophilic addition reactions
- DNucleophilic addition reactions
$C{H_3} - CH = C{H_2} + {H^ + } \xrightarrow{Slow} \mathop {C{H_3} - \mathop C\limits^ + H - C{H_3}}\limits_{{2^o}{\rm{ carbonium ion}}} $
$C{H_3} - \mathop {{\text{ }}C}\limits^ + H - C{H_3} + B{r^ - }\xrightarrow{{Fast}}$ $\mathop {\begin{array}{*{20}{c}}
{C{H_3} - CH - C{H_3}} \\
{|\,\,\,\,} \\
{\,Br\,\,\,}
\end{array}}\limits_{2 - Bromopropane} $
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Statement $(I)$ : The $4 \mathrm{f}$ and $5 \mathrm{f}$ - series of elements are placed separately in the Periodic table to preserve the principle of classification.
Statement $(II)$ :$S$-block elements can be found in pure form in nature. In the light of the above statements, choose the most appropriate answer from the options given below :