Which of the following constitutes a neutral hydride?

The concept of neutral hydrides refers to compounds formed between hydrogen and other elements that do not carry a net charge. In this context, the correct answer, which is methane (CH₄), is recognized as a neutral hydride because it is formed by the covalent bonding of carbon and hydrogen. In this molecule, carbon shares electrons with four hydrogen atoms, resulting in a stable arrangement without any overall charge.

In contrast, hydrogen chloride (HCl) is an acid that dissociates in solution to produce H⁺ and Cl⁻ ions, making it a polar compound rather than a neutral hydride. Potassium hydride (KIn) consists of potassium and hydrogen where potassium typically exists as a cation (K⁺), which leads to an ionic compound that is not neutral. Magnesium hydride (MgH₂), while it contains hydrogen, consists of magnesium in a +2 oxidation state and hydrogen in a -1 oxidation state, resulting in an ionic nature that also does not qualify as a neutral hydride.

Methane exemplifies a neutral hydride due to its covalent bonding and lack of charge, satisfying the definition in the context of this question.