Due to the presence of an unpaired electron,free radicals are .........

The correct order of the relative stability of the following carbanions is:
$I$. $HC \equiv C^{-}$
$II$. $CH_2=CH-CH_2^{-}$
$III$. $H_2C=CH^{-}$
$IV$. $(C_6H_5)_2CH^{-}$

The incorrect statement about carbene $(CH_2)$ is:

Which of the following is the most stable carbocation?

When do positive and negative charges appear on a carbon atom? Give examples.

Match the List-$I$ with List-$II$:

$A$. Carbocation	$I$. Species that can supply a pair of electrons.
$B$. Carbon free radical	$II$. Species that can receive a pair of electrons.
$C$. Nucleophile	$III$. $sp^2$ hybridized carbon with empty $p$-orbital.
$D$. Electrophile	$IV$. $sp^2/sp^3$ hybridized carbon with one unpaired electron.

Choose the correct answer from the options given below: