`CH_(3)-CHCl-CH-CH_(3)` has a chiral centre. Which one of the following represent its `R`-configuration?

Options

A. `H-overset(C_(2)H_(5))overset(|)underset(Cl)underset(|)(C)-CH_(3)`
B. `Cl-overset(C_(2)H_(5))overset(|)underset(H)underset(|)(C)-CH_(3)`
C. `H-overset(CH_(3))overset(|)underset(C_(2)H_(5))underset(|)(C)-Cl`
D. `H_(3)C-overset(C_(2)H_(5))overset(|)underset(H)underset(|)(C)-Cl`

Answer

B

Explanation

Follow priority rule.

Golden rule: If `4^(th)` priority groups is vertical then `R` is `R`. If `4^(th)` priority group is horizontal, then `RgtS` and `StoR`.