The molecule which has a linear shape is

Step 1: Analyze the question We need the molecule whose atoms lie in a straight line (bond angle 180°). Shape depends on the number of electron pairs around the central atom (VSEPR theory).

Step 2: Concept (VSEPR) Electron pairs around a central atom repel each other and spread as far apart as possible:

• 4 bond pairs, 0 lone pairs → tetrahedral
• 3 bond pairs, 1 lone pair → pyramidal
• 2 bond pairs, 2 lone pairs → bent (V-shaped)
• 2 bonding regions, 0 lone pairs → linear

Step 3: Check each option

• A. CH₄: Carbon has 4 bond pairs and no lone pairs, so the shape is tetrahedral (109.5°). Not linear.
• B. NH₃: Nitrogen has 3 bond pairs and 1 lone pair, so the shape is pyramidal (about 107°). Not linear.
• C. H₂S: Sulphur has 2 bond pairs and 2 lone pairs, so the shape is bent/V-shaped (about 92°). Not linear.
• D. CO₂: Structure is O=C=O. Carbon forms two double bonds and has no lone pairs. With only two regions of electron density, they sit opposite each other at 180°, so the molecule is linear.

Step 4: Answer The linear molecule is CO₂, which is option D.

Tip: Remember that linear molecules usually have a central atom with no lone pairs and just two bonded atoms, such as CO₂, BeCl₂, and C₂H₂. If you see lone pairs on the central atom in a small molecule like H₂O, H₂S or NH₃, the shape will be bent or pyramidal, not linear.