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

Total number of possible stereoisomers of dimethylcyclopentane is $....$

Determine the configuration of the chiral centers in the given structure.

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

Give the name and structure of the following:
$(i)$ Chain isomers of pentane $(C_5H_{12})$
$(ii)$ Isomers of $C_3H_8O$
$(iii)$ Isomers of $C_3H_6O$
$(iv)$ Metamers in $C_4H_{10}O$

Identify the conformer of $2$-methylpentane.