State whether the following statements are True or False:
$(i)$ $CH_3-CH_2^+$ is more stable than $CH_3^+$
$(ii)$ $CH_3-CH_2^+$ is less stable than $CH_3^+$
$(iii)$ $(CH_3)_3C^+$ is less stable than $CH_3^+$
$(iv)$ $(CH_3)_3C^+$ is more stable than $CH_3^+$

(A) The stability of carbocations is determined by the inductive effect and hyperconjugation. The order of stability is: $3^\circ > 2^\circ > 1^\circ > \text{methyl carbocation}$.
$(i)$ $CH_3-CH_2^+$ $(1^\circ)$ is more stable than $CH_3^+$ (methyl) due to the $+I$ effect of the methyl group. Statement is True $(T)$.
$(ii)$ $CH_3-CH_2^+$ is more stable than $CH_3^+$,so the statement that it is less stable is False $(F)$.
$(iii)$ $(CH_3)_3C^+$ $(3^\circ)$ is significantly more stable than $CH_3^+$ due to hyperconjugation and $+I$ effect. Statement is False $(F)$.
$(iv)$ $(CH_3)_3C^+$ is more stable than $CH_3^+$. Statement is True $(T)$.
Final answer: $(i-T, ii-F, iii-F, iv-T)$.