To determine if a molecule is linear, we need to analyze its hybridization and molecular geometry using VSEPR theory.

VSEPR (Valence Shell Electron Pair Repulsion) theory predicts the geometry of molecules based on minimizing the repulsion between electron pairs in the valence shell of the central atom. The number of electron domains (lone pairs + bonding pairs) around the central atom determines its hybridization and thus its geometry.

Let's analyze each option:

• A) BeF\u2082: The central atom is Beryllium (Be). Be has 2 valence electrons. It forms two single bonds with two Fluorine (F) atoms. There are no lone pairs on Be. Thus, there are 2 electron domains around Be. This corresponds to sp hybridization and a linear geometry.
• B) BeH\u2082: Similar to BeF\u2082, the central atom is Beryllium (Be). Be forms two single bonds with two Hydrogen (H) atoms. There are no lone pairs on Be. Thus, there are 2 electron domains around Be. This corresponds to sp hybridization and a linear geometry.
• C) CO\u2082: The central atom is Carbon (C). Carbon forms two double bonds with two Oxygen (O) atoms. There are no lone pairs on C. Each double bond counts as one electron domain. Thus, there are 2 electron domains around C. This corresponds to sp hybridization and a linear geometry.
• D) H\u2082O: The central atom is Oxygen (O). Oxygen has 6 valence electrons. It forms two single bonds with two Hydrogen (H) atoms. This leaves $6-2=4$ electrons, which form two lone pairs on Oxygen. Thus, there are 4 electron domains (2 bonding pairs + 2 lone pairs) around O. This corresponds to sp\u00b3 hybridization. Due to the presence of two lone pairs, the molecular geometry is bent (or V-shaped), not linear. The bond angle is approximately 104.5\u00b0.

Therefore, H\u2082O is not linear.

Correct Answer: (D)