Only HF and HMnO₄ are acids and all others are base.
When the given substances are put in water, they break apart to give H⁺ or OH⁻ ions. Only HF and HMnO₄ will give H⁺ ions and others will give OH⁻ ions. It is these ions which give a substance its acidic or basic nature. All the substances that give H⁺ ions are acidic in nature. The others that give OH⁻ ions are basic in nature.
