Question

Which of the following pairs is considered to be isoelectronic?

1. Xe and I

2. K and Ar

3. H and Li

4. Br – and Kr

Which of the following compounds demonstrates an exception to the octet rule?

1. KCl

2. H2O

3. SF6

4. C2H6

In which of the following substances would you expect to find ionic bonding?

1. CH3Cl

2. SO2

3. HCl

4. KCl

Using VSEPR theory, predict the shape of a molecule with 3 bonding pairs and no lone pairs of electrons.

1. bent

2. trigonal pyramidal

3. tetrahedral

4. trigonal planar

Predict which of the following molecules will demonstrate the least polarity.

1. SeCl4

2. CO

3. O2

4. ClO–

Answer 1

1.

Br^- has 36 electrons

Kr also has 36 electrons.

Hence, Br^- and Kr are isoelectronic.

2.

In SF₆ , total valence electrons around sulfur = 12.

Hence, it violates octet rule.

3.

Ionic bonding is formed between metal and nonmetals.

KCl has ionic bonding, as K is alkali metal and Cl is nonmetal.

4.

3 bonding and no lone pairs of electrons , hence hybridization is sp², and geometry is trigonal planar.

5.

Shape of SeCl₄ is seasaw, hence polar.

CO is polar.

ClO^- is polar. bonding between atoms of two different elements is polar.

But bonding between atoms of same element is nonpolar.

Hence O₂ has least polarity .