$1.\,\,(CH_3)_2 - \mathop C\limits^ + - CH_2 - CH_3$
$2.\,\,(CH_3)_3 - \mathop C\limits^ + $
$3.\,\,(CH_3)_2 - |\mathop C\limits^ + H|$
$4.\,\,CH_3 - \mathop C\limits^ + H_2$
$5.\,\,\mathop C\limits^ + H_3$
\(<1^{\circ}<2^{\circ}<3^{\circ}\)
Given carbocations \((\mathrm{CH} _3) _3 \mathrm{C} \cdot \Rightarrow 3^{\circ}\) carbocation
\((\mathrm{CH} _3) _2 \mathrm{CH} \cdot=>2^{\circ}\) carbocation
\(\mathrm{CH} _3 \mathrm{CH} _2 \cdot \Rightarrow 1^{\circ}\) carbocation
Therefore, increasing order of stability of carbocations \(\mathrm{CH} _3 \mathrm{CH}_ 2 \cdot\left(1^{\circ}\right)<(\mathrm{CH}_ 3) _2 \mathrm{CH} \cdot\left(2^{\circ}\right)<(\mathrm{CH}_3)_ 3 \mathrm{C} \cdot\left(3^{\circ}\right)\)


$(1)$ $C{H_3} - \mathop {CH}\limits^| - {C_2}{H_5}$
$(2)$ $C{H_2} = \,\mathop C\limits^| \, - \,\,C{H_3}$
$(3)$ $ CH_2 = CH -$
$(4)$ $(CH_3)_2 CH -$

