Which hydride is known to be basic?

The hydride that is known to be basic is ammonia, NH₃. Ammonia acts as a base because it can accept a proton (H⁺) from an acid, thereby forming the ammonium ion (NH₄⁺). This behavior is consistent with the Bronsted-Lowry definition of bases, where a base is a substance that can accept protons.

In contrast, the other compounds listed do not exhibit basic behavior in the same way. Methane (CH₄) is a neutral compound and does not have a tendency to accept protons, making it non-basic. Potassium fluoride (KF) is an ionic compound that dissociates in solution to give K⁺ and F⁻ ions, where F⁻ can act as a weak base in the context of fluoride accepting protons, but it is not a hydride. Hydrogen sulfide (H₂S) can behave as a weak acid rather than a base, as it can donate protons to form HS⁻, but it does not act as a base by retaining protons. Therefore, ammonia stands out as the classic example of a basic hydride due to its ability to accept protons and participate in reactions characteristic of bases