Circles represent the most acidic hydrogens in these molecules. Which of the following is the correct representation?

Rank the following substances in order of decreasing heat of combustion (maximum $\to$ minimum).

Which of the following compounds is chiral?

The number of stereoisomers possible for $1,2-$dimethylcyclopropane is:

After prolonged treatment of $(A)$ by $D_2O/DO^-$, the difference in molecular weights of compounds $(A)$ and $(B)$ is:

Consider the sets $I$,$II$,and $III$. Identify the set$(s)$ which is (are) correctly matched.
$I$. $\text{Staggered ethane} > \text{eclipsed ethane} \dots \dots \dots \text{torsional strain}$.
$II$. $2, 2-\text{Dimethylbutane} > 2-\text{methylpentane} \dots \dots \dots \text{boiling point}$.
$III$. $cis-\text{but}-2-\text{ene} > trans-\text{but}-2-\text{ene} \dots \dots \dots \text{dipole moment}$.