Formation of PH4^+ ion is relatively difficult in comparison to NH4^+ ion. — Chemical Bonding Chemistry Question

💡 Solution & Explanation

Step 1: Analyze the geometries of the given species. NCO^- is linear (sp hybridized central carbon). CS2 is linear (sp hybridized central carbon, analogous to CO2). NO2^+ is linear (sp hybridized nitrogen, with 0 lone pairs). Step 2: For BeH2, in the gaseous state, monomeric BeH2 is linear. However, in the solid state, BeH2 polymerizes via 3-center-2-electron Be-H-Be bridge bonds into a tetrahedral network (non-linear chain). Step 3: Thus, only NCO^-, CS2, and NO2^+ assume a linear structure, making (c) the correct option.