Question

Which one of the following statement is true for ammonium ion
A) All bonds are ionic
B) All bonds are coordinate covalent
C) H atoms are situated at the corners of a square
D) H atoms are situated at the corners of a tetrahedron

Answer 1

Hint: When an ammonia molecule acquires a proton, then an ammonium ion forms. The molecular formula of ammonium ion is \[{\rm{N}}{{\rm{H}}_{\rm{4}}}^ + \] . Here, first we will discuss all types of bond so that we will identify the type of bond in the ammonium ion.

Complete step by step solution:Let’s understand what an ionic bond is. This type of bond is formed due to the electrostatic attraction of oppositely charged ions. For example, sodium chloride is an ionic bond.
Now we will discuss what a coordinate bond is. A bond whose formation takes place due to the donation of both the electrons by an atom is called a coordinate bond.
A covalent bond is the one in which the bond formation takes place due to the sharing of electrons between the atoms.
Let’s understand the ammonium ion.

Image: Ammonium ion
In the ammonium three N-H bonds are covalent in nature because they formed due to the sharing of electrons. And the bond denoted by the arrow bond is a coordinate bond.
So, in the ammonia ion three covalent bonds and one coordinate bond are present.
Let’s find the shape of \[{\rm{N}}{{\rm{H}}_{\rm{4}}}^ + \]. It is \[s{p^3}\] hybridized and therefore its molecular geometry is tetrahedral. Therefore, each hydrogen atom occupies the corners of a tetrahedron.

So, option D is right.

Note: The shape of a molecule is decided by applying the VSEPR theory. According to this theory, if we know the count of bond pairs and the lone pairs of a central atom, we can easily identify its shape.