Which of the following are secondary radicals?
$(1) \ CH_3 - \dot{C}H - C_2H_5$
$(2) \ CH_2 = \dot{C} - CH_3$
$(3) \ CH_2 = CH - \dot{C}H_2$
$(4) \ (CH_3)_2 \dot{C}H$

Arrange the following cations in decreasing order of their stability:
$(a)$ $CH_3^+$
$(b)$ $F-CH_2-CH_2^+$
$(c)$ $Br-CH_2-CH_2^+$
$(d)$ $CH_3-CH_2-CH_2^+$

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

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 order of stability of the carbocations given below is:

Among the given pairs,in which pair does the second compound have less enol content than the first compound?