Question

S1: $${\text{I}}_3^{+}$$ is a linear molecule with two lone pairs of electrons on a central atom.
S2: $${\text{I}}_2$$ is a linear molecule with three lone pairs of electrons on a central atom.
S3: $${\text{IBr}}_4^{+}$$ is a bent molecule with two lone pairs of electrons on the central atom.
S4: $${\text{ICl}}_4^{-}$$ is a pyramidal molecule with one lone pair of electrons on a central atom. Which of the following options is true if T represents true and F as false.
(A) TFTF
(B) FTFT
(C) TFFT
(D) FTFF

Answer 1

Hint: To solve such types of questions we need to first determine the number of valence electrons present in the central atom. Then determine the steric number, hybridization and geometry.

Step by step answer: Iodine belongs to the halogen family with seven valence electrons.
The central iodine atom in $${\text{I}}_3^{+}$$ ion has six valence electrons as it has lost one valence electron due to positive charge. The central iodine atom has two bond pairs and two lone pairs of electrons. It undergoes $$s{p}^3$$ hybridization. The electron pair geometry is tetrahedral and the molecular geometry is bent of V shaped
 $${\text{I}}_3^{+}$$ is a bent molecule with two lone pairs of electrons on the central atom.
Hence, the statement S1 is false.
In $${\text{I}}_2$$ molecules, the central iodine atom has seven valence electrons. The central iodine atom has one bond pair and three lone pairs of electrons. It undergoes $$s{p}^3$$ hybridization. The electron pair geometry is tetrahedral and the molecular geometry is linear.
$${\text{I}}_2$$ is a linear molecule with three lone pairs of electrons on a central atom.
Hence, the statement S2 is true.
In $${\text{IBr}}_4^{+}$$ molecule, the central iodine atom has six valence electrons as it has lost one valence electron due to positive charge. The central iodine atom has one lone pair and four bond pairs of electrons. It undergoes $$s{p}^{3}d$$ hybridization. The electron pair geometry is trigonal bipyramidal and the ionic geometry is seesaw.
Hence, the statement S3 is false.

In $${\text{ICl}}_4^{-}$$ molecule, the central iodine atom has eight valence electrons as it has gained one valence electron due to negative charge. The central iodine atom has two lone pairs and four bond pairs of electrons. It undergoes $$s{p}^3{d}^2$$ hybridization. The electron pair geometry is octahedral and the ionic geometry is square planar.
Hence, the statement S4 is false.

Hence option D is correct.

Note: Steric number is the sum of the number of bond pairs and lone pairs of electrons. The hybridisation can be determined from the steric number. For example, a steric number of 4 is associated with $$s{p}^3$$ hybridization and tetrahedral electron pair geometry. Steric number of 4 corresponds to 4 bond pairs, 3 bond pairs and one lone pair or two bond pairs and two lone pairs of electrons.