Consider thiol anion `(RS^(Theta))` and alkoxy anion `(RO^(Theta))`. Which of the following statements is correct?

Options

A. `RS^("Ө")` is less basic and less nucleophilic than `RO^("Ө")`
B. `RS^("Ө")` is less basic but more nucleophilic than `RO^("Ө")`
C. `RS^("Ө")` is more basic and more nucleophilic than `RO^("Ө")`
D. `RS^("Ө")` is more basic but less nucleophilic than `RO^("Ө")`

Answer

B

Explanation

Nucleophilic strength increases down the group due to large size of nucleophilic atom. The basicity decreases down the group due to dispersal of electron density over large size of atom.
e.g., `I^(-) gt Br^(-) gt Cl^(-) gt F^(-)` decreasing nucleophilic strength and `I^(-) lt Br^(-) lt Cl^(-) lt F^(-)` increasing basic strength. This is the order in polar protic solvents `(H_(2)O, ROH and RCOOH)`.
Hence in present case, `RO^(-) lt RS^(-)` (Nucleophilic strength) and `RS^(-) lt RO^(-)` (Basic strength).