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

What is the fission of a covalent bond? Explain its types with examples and the main differences.

Show the heterolytic and homolytic cleavage of $H_3C-Br$.

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

Match the reactions in column $I$ with appropriate types of steps/reactive intermediate involved in these reactions as given in column $II$.
| Column $I$ | Column $II$ |
| :--- | :--- |
| $(A)$ $1-$phenylpentane$-1,4-$dione $\xrightarrow{aq. NaOH}$ $3-$phenylcyclopent$-2-$en$-1-$one | $(p)$ Nucleophilic substitution |
| $(B)$ $4-$chloro$-1-$phenylbutan$-1-$one $\xrightarrow{CH_3MgI}$ $2-$methyl$-2-$phenyltetrahydrofuran | $(q)$ Electrophilic substitution |
| $(C)$ $4-$hydroxy$-1-$phenylbutan$-1-$one $\xrightarrow{H_2SO_4}$ $2-$phenyl$-4,5-$dihydrofuran | $(r)$ Dehydration |
| $(D)$ $4-$methyl$-4-$phenylpentan$-1-$ol $\xrightarrow{H_2SO_4}$ $1,1-$dimethyl$-1,2,3,4-$tetrahydronaphthalene | $(s)$ Nucleophilic addition |
| | $(t)$ Carbanion |

Which kind of fission is favoured by sunlight?