In the following reaction,which type of reaction intermediate is likely to be involved?

Arrange the following anions in decreasing order of their stability:
$CH_3^{\Theta}, NH_2^{\Theta}, OH^{\Theta}, Cl^{\Theta}$

The orbital picture of a singlet carbene $(:CH_2)$ can be drawn as:

$p$ will be

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:

The correct stability order for the following species is: