$1.\,\,(CH_3)_2 - \mathop C\limits^ + - CH_2 - CH_3$
$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 $\mathrm{CH} _3 \mathrm{CH}_ 2 \cdot\left(1^{\circ}\right)<(\mathrm{CH}_ 3) _2 \mathrm{CH} \cdot\left(2^{\circ}\right)<(\mathrm{CH}_3)_ 3 \mathrm{C} \cdot\left(3^{\circ}\right)$
$(CH_3)_3 \, \overline C , \overline C Cl_3 ,(CH_3 )_2 \overline C H ,C_6 H_5 \overline C H_2$
$1.$ $HCHO$
$2.$ $ CH_3COCH_3$
$3.$ $PhCOCH_3$
$4.$ $PhCOPh$
$(I)\,\,C{H_2} = CH - \mathop C\limits^ \oplus {H_2}$
$(II)\,\,C{H_3} - CH_2 - \mathop C\limits^ \oplus {H_2}$
$I$ $ -OAc$
$II$ $-OMe$
$III$ $-OSO_2Me$
$IV$ $OSO_2CF_3$