In a reaction,if half of the double bond is broken and two new bonds are formed,this is a case of

What are the main types of organic reactions and their mechanisms?

Match Column-$I$ and Column-$II$ with the correct relation:

Column-$I$	Column-$II$
$(i)$ Substitution reaction	$(p)$ $CH_2=CH_2 + Br_2 \to CH_2Br-CH_2Br$
$(ii)$ Addition reaction	$(q)$ $C_6H_6 + NO_2^+ \to C_6H_5NO_2 + H^+$
$(iii)$ Electrophilic addition reaction	$(r)$ $CH_3Cl + NaOH \to CH_3OH + NaCl$
$(iv)$ Electrophilic substitution reaction	$(s)$ $CH_3CH_2OH \xrightarrow[\Delta]{Al_2O_3} CH_2=CH_2$
$(v)$ Elimination reaction

The order of decreasing reactivity in electrophilic addition of the following compounds is
$(I) \, Ph-CH=CH-COOH$
$(II) \, p-NO_2-C_6H_4-CH=CH-COOH$
$(III) \, p-MeO-C_6H_4-CH=CH-COOH$
$(IV) \, p-Cl-C_6H_4-CH=CH-COOH$

In the following reaction,compound $Q$ is obtained from compound $P$ via an ionic intermediate. What is the degree of unsaturation of $Q$?

Match the reactions in Column-$(I)$ with the type of reaction mechanism in Column-$(II)$.

Column-$(I)$ (Reaction)	Column-$(II)$ (Type of Reaction)
$(A)$ $\text{Cyclohexene} + Br_2 \xrightarrow{\Delta, uv} \text{3-Bromocyclohexene}$	$(i)$ $\text{Nucleophilic substitution}$
$(B)$ $\text{4-Hydroxybenzyl alcohol} + HCl \xrightarrow{\Delta} \text{4-Hydroxybenzyl chloride}$	$(ii)$ $\text{Electrophilic addition}$
$(C)$ $\text{Cyclohexene} + Br_2 \xrightarrow{CCl_4} \text{1,2-Dibromocyclohexane}$	$(iii)$ $\text{Free radical substitution}$
$(D)$ $\text{Toluene} + Cl_2 \xrightarrow{Fe, \text{dark}} \text{o/p-Chlorotoluene}$	$(iv)$ $\text{Electrophilic aromatic substitution}$