The electron pair geometry of a molecule is tetrahedral. what is its bond angle if it shows one lone pair of electrons and three bonding pairs?

a) less than 109.5°
b) more than 109.5°
c) equal to 109.5°
d) zero

 A) Less than 109.5°

Explanation: The electron pair geometry of a molecule is tetrahedral , which means the number of electrons is 4 that means the hybridization will be . and the bond angle will be 109.5°.

But as one lone pair of electrons and three bonding pairs are present, the fourth position will be occupied by lone pair of electrons. The repulsion between lone and bond pair of electrons is more and hence the bond angle will decrease from 109.5° and molecular geometry will be trigonal pyramidal.

As in ammonia molecule, the bond angle reduces to 107° due to the presence of lone pair of electron in tetrahedral geometry.