The order of circled $C-H$ bond dissociation energy in the following compounds is:

Among the following carbocations:
$(I)$ $Ph_{2}\stackrel{+}{C} CH_{2} Me$
$(II)$ $Ph CH_{2} CH_{2} \stackrel{+}{C} HPh$
$(III)$ $Ph_{2} CH \stackrel{+}{C} HMe$
$(IV)$ $Ph_{2} C(Me) \stackrel{+}{C} H_{2}$
The order of stability is:

Compare the stability of the following free radicals:
$(1)$ $CH_3 - \dot{CH} - CH_3$
$(2)$ $C_6H_5 - \dot{CH_2}$
$(3)$ $\dot{CH_2} - CH(CH_3)_2$
$(4)$ $\dot{CH_2} - CH_3$

Rank the transition states that occur during the following reaction steps in order of increasing stability (least $\to$ most stable):
$1. CH_3-OH_2^+ \to CH_3^+ + H_2O$
$2. (CH_3)_3C-OH_2^+ \to (CH_3)_3C^+ + H_2O$
$3. (CH_3)_2CH-OH_2^+ \to (CH_3)_2CH^+ + H_2O$

Explain why $((CH_3)_3C)^+$ is more stable than $(CH_3CH_2)^+$ and $(CH_3)^+$ is the least stable carbocation.

Among the following, which is the most stable carbocation?