Which one among the following carbocations is the most stable?

Stability order of the following carbocations is:
$(i)$ $CH_3-C^{+}(CH_3)-CH_2-CH_3$
$(ii)$ $CH_3-CH^{+}-CH_3$
$(iii)$ $CH_3-C^{+}(CH_3)-CH_3$
$(iv)$ $Ph-CH^{+}-CH_3$

Which amongst the following is the most stable carbocation?

In the following species, the one which is likely to be the intermediate during benzoin condensation of benzaldehyde is

Which free radical is most stable among the following?

Arrange the following carbanions in the decreasing order of stability:
$I. \ p-Br-C_6H_4-CH_2^-$
$II. \ C_6H_5-CH_2^-$
$III. \ p-CH_3O-C_6H_4-CH_2^-$
$IV. \ p-CHO-C_6H_4-CH_2^-$
$V. \ p-CH_3-C_6H_4-CH_2^-$
Choose the correct answer from the options given below: