In the potential energy diagram shown,the point $X$ represents:

The increasing order of basicity for the following intermediates is (from weak to strong):
$(i)$ $(CH_3)_3C^{-}$
$(ii)$ $H_2C=CH-CH_2^{-}$
$(iii)$ $HC \equiv C^{-}$
$(iv)$ $CH_3^{-}$
$(v)$ $CN^{-}$

Which of the following carbocations is the most stable?

Using curved-arrow notation,show the formation of reactive intermediates when the following covalent bonds undergo heterolytic cleavage:
$(a)$ $CH_{3}-SCH_{3}$
$(b)$ $CH_{3}-CN$
$(c)$ $CH_{3}-Cu$

The correct order of decreasing stability of the following carbocations is:
$I. CH_3-CH^{+}-CH_3$
$II. CH_3-CH^{+}-OCH_3$
$III. CH_3-CH^{+}-CH_2-OCH_3$

Which of the following is an incorrect stability order?