Arrange the following in decreasing order of stability.
$(i)$ $CH_3^{\bullet}$,$(CH_3)_3C^{\bullet}$,$(CH_3)_2CH^{\bullet}$ and $CH_3CH_2^{\bullet}$
$(ii)$ $CH_3CH_2^{+}$,$(CH_3)_3C^{+}$,$(CH_3)_2CH^{+}$ and $CH_3^{+}$

(N/A) $(i)$ The stability of free radicals increases with the number of alkyl groups attached to the radical carbon due to hyperconjugation and inductive effect: $(CH_3)_3C^{\bullet} > (CH_3)_2CH^{\bullet} > CH_3CH_2^{\bullet} > CH_3^{\bullet}$.
$(ii)$ The stability of carbocations increases with the number of alkyl groups attached to the positive carbon due to hyperconjugation and inductive effect: $(CH_3)_3C^{+} > (CH_3)_2CH^{+} > CH_3CH_2^{+} > CH_3^{+}$.