Which of the following carbanions is the least stable?

Arrange the following carbocations in decreasing order of their stability:
$\stackrel{+}{C}H_3, (CH_3)_3\stackrel{+}{C}, CH_3\stackrel{+}{C}H_2, (CH_3)_2\stackrel{+}{C}H$

The bond dissociation energy of the $C-H$ bond for the compounds: $(I)\ CH_3-H, (II)\ CH_3-CH_2-H, (III)\ CH_2=CH-CH_2-H, (IV)\ C_6H_5-H$ follows the order:

Which of the following is the most stable cation?

Which is the decreasing order of stability?
$(i)$ $CH_3-CH^{+}-CH_3$
$(ii)$ $CH_3-CH^{+}-OCH_3$
$(iii)$ $CH_3-CH^{+}-COCH_3$

Which of the following is most stable?