Why is 0.15 M of hypochlorous acid acidic and 0.15 M of sodium hypochlorite basic?

As the name hypochlorous acid suggest that it is acidic, no matter what is the concentration of the acid, the acid solution is acidic as it provides hydronium or hydrogen ions to the aqueous solution.

HClO (aq) ↔ H⁺ (aq) + ClO⁻ (aq)

Hypochlorous acid or HClO is a weak acid, while NaOH is a strong base. The formation of NaOCl takes place when these two react. NaOCl is a salt of a strong base and a weak acid, and due to this, the solution of sodium hypochlorite is basic.

Sodium is the spectator ion, that is, it does not need to be represented at the time of demonstrating the net equation for the hydrolysis of sodium hypochlorite.

ClO⁻ (aq) + H2O (l) ↔ HOCl (aq) + OH⁻ (aq)

On observing the first equation, on the product side, there are hydrogen ions, which signifies that the solution is acidic, and if we observe at the second equation, on the product side hydroxide ion is witnessed that indicates that the solution is basic.