JEE Main · 2023 · 31 Jan 2023 · Shift 2 · Chemical Bonding and Molecular Structure

A species is linear when the two bonding directions on the central atom lie at $180^{\circ }$. Xenon difluoride has two bond pairs and three lone pairs in a trigonal bipyramid with the lone pairs equatorial, giving a linear shape, and the triiodide anion is linear for the same reason. Carbon dioxide and beryllium chloride each have two bond pairs with no lone pair on an $sp$ centre, and carbon suboxide $\mathrm{O}=\mathrm{C}=\mathrm{C}=\mathrm{C}=\mathrm{O}$ has every carbon $sp$, so all three are linear. The triiodide cation with two lone pairs, sulphur dioxide with one lone pair, and $\mathrm{BC}{\mathrm{l}}_2^{-}$ with one lone pair are all bent. The number of linear species is five.