UPSC CDS I 2019 GK Paper

In a tetrahedral molecule, a central atom is located at the centre with four substituents that are located at the corners of a tetrahedron, e.g., CH3F (Fluoromethane). In a trigonal planar, one atom remains at the centre and the rest three atoms at the corners of an equilateral triangle, e.g., HCHO (Formaldehyde). In a linear molecule, the central atom bonds with two other atoms at a bond–angle of 180°, e.g., HCN. In a trigonal pyramid, a central atom bonds with three other atoms in the pyramidical shape, e.g., NH3 (Ammonia).