Courses
Courses for Kids
Free study material
Offline Centres
More
Store

# Among the following which has trigonal pyramidal geometry?A.${\text{B}}{{\text{H}}_3}$B.${{\text{H}}_2}{\text{O}}$C.${\text{C}}{{\text{H}}_4}$D.${\text{N}}{{\text{H}}_3}$E.${\text{AlC}}{{\text{l}}_3}$

Last updated date: 17th Jul 2024
Total views: 62.1k
Views today: 1.62k
In ${\text{B}}{{\text{H}}_3}$ and ${\text{AlC}}{{\text{l}}_3}$since 3 hydrogen atoms are attached that means 3 bond pair of electrons are present, but boron and aluminium have no lone pairs. They are group 13 elements and hence have valency 3 and no other electrons. So this option is eliminated.
In ${{\text{H}}_2}{\text{O}}$ oxygen have 6 electrons, out of which 2 electrons bonded with hydrogen will form 2 bond pair and rest will make 2 lone pair of electrons, which is not required and hence this option stands wrong.
In ${\text{C}}{{\text{H}}_4}$ carbon has 4 electron and all are bonding so no lone pair are present here.
In ${\text{N}}{{\text{H}}_3}$ nitrogen has 5 electrons in its valance shell and hence is bonded with 3 hydrogen atoms. That makes 3 bond pair and one lone pair and hence ${\text{N}}{{\text{H}}_3}$ had trigonal geometry.
Note: Often geometry and shape are confused. We generally use them as same. Actually geometry of ${{\text{H}}_2}{\text{O}}$, ${\text{C}}{{\text{H}}_4}$ and ${\text{N}}{{\text{H}}_3}$is same that is tetrahedral but their shapes vary. Water has bent shape where as methane has tetrahedral shape and ammonia has trigonal pyramidal shape. Geometry includes both lone pair and bond pair while shape only includes bond pairs.