Basic terminology: H2O and CH4 are correctly classified as which type of chemical entities?

Introduction / Context: Properly naming chemical entities is foundational. Water (H2O) and methane (CH4) are classic examples of neutral covalent compounds composed of atoms held together by shared electron pairs.

Given Data / Assumptions:

• Both substances at standard conditions (25 °C, 1 atm).
• We focus on intrinsic bonding and charge.

Concept / Approach: A molecule is a discrete aggregate of atoms bound by covalent bonds with no net charge. Ions, by contrast, are charged species (e.g., Na+, Cl–). While water can act as acid or base depending on context (amphoteric), it is not inherently always an acid. Methane is a nonpolar molecule under normal conditions.

Step-by-Step Solution: Identify bonding → O–H and C–H bonds are covalent. Check net charge → neither water nor methane carries net charge in their neutral forms. Therefore, they are molecules. Other classifications are context dependent or incorrect.

Verification / Alternative check: Spectroscopic and structural data (bond lengths, bond angles) confirm discrete molecular structures for both H2O and CH4.

Why Other Options Are Wrong: Option B (ions) is false; option C (acids in every context) is incorrect—water is amphoteric, methane is extremely weakly acidic; “none” is wrong; radicals would require unpaired electrons, which are absent.

Common Pitfalls: Equating acidity with molecular identity; confusing ionic compounds with covalent molecules.

Final Answer: Molecules (discrete covalently bonded species).