ICSE Class 10 Answered

(1) Tetrahedral structure: 

Methane: an example of tetrahedral geometry. The carbon has 4 valence electrons and thus needs 4 more electrons from four hydrogen atoms to complete its octet. The hydrogen atoms are as far apart as possible at 109^o bond angle.

(2) Planar structure:

Boron trifluoride: an example of trigonal planner geometry. The boron has 3 valence electrons and these orbitals hybridized to sp² and formed three same energy sp² hybridized orbitals are coplanar and lying 120^o apart, each containing one electron. These hybrid orbitals then overlap with the half-filled p-orbitals of three fluorine atoms forming three co-planer B-F electron pair bonds.

(3) Linear structure:

Carbon dioxide: It is an example of linear molecules. In this C is sp² Hybridized to form hybrid orbitals which is overlapped by oxygen atom resulting in the formation of the double bond with linear geometry and 180^o bond angle.