Question

The oxyacid of sulphur that contains a lone pair of electrons on sulphur is:
a.) Sulphurous acid
b.) Sulphuric acid
c.) Peroxodisulphuric acid
d.) Pyro sulphuric acid

Answer 1

Hint: -Sulphur has a tetrahedral structure with respect to oxygen in oxoacids. Generally, these oxoacids have at least one $S~=~O~$ bond and one $S-OH~$ bond. Oxyacid (also known as oxyacids) is an acid that contains an oxygen atom attached to a hydrogen atom and at least one other element.

Complete answer: Here’s the chemical formula for the given compound

 Sulphurous Acid ${{H}_{2}}S{{O}_{3}}$
Sulphuric Acid ${{H}_{2}}S{{O}_{4}}$
Peroxymonosulfuric Acid ${{H}_{2}}S{{O}_{5}}$
Pyrosulphuric Acid ${{H}_{2}}{{S}_{2}}{{O}_{7}}$
Where lone pair refers to a pair of valence electrons that are not shared with another atom in a covalent bond and is often referred to as a nonbonding pair or pair. Lone pairs are found in the atom shell of the outermost electron.
Oxoacids are oxygen containing acids. Sulphur is known to form many oxoacids, such as ${{H}_{2}}S{{O}_{4}}$,${{H}_{2}}S{{O}_{3}}$ etc. Sulphur shows a tetrahedral structure when coordinated with oxygen in sulphur oxoacids. Sulphur oxoacids typically contain at least one $S~=~O~$ bond and one $S-OH~$ bond. Terminal peroxide clusters, terminal $S~=~S$, terminal and bridging oxygen atoms and chains$\left( -S- \right)n~$ are also observed in addition to $S~=~S$ and $S-OH~$.
Sulphur oxyacids, which contains a single pair of sulphide electrons, is sulphuric acid ${{H}_{2}}S{{O}_{3}}$ In which only 4 valence electrons are involved in bonding the remaining 2 electrons remain as a single pair of sulphur (Sulphur has six valence electrons).
So, the correct answer is “Option A”.

Note: Oxyacid dissociates in water to form the ${{H}^{+~}}$ cation and the acid anion. Oxyacids have a general $X-O-H~$ shape.
Electron pairs are also known to be lone pairs if two electrons are paired but are not used in chemical bonding. Therefore, the number of single pair electrons plus the number of bonding electrons is equal to the total number of valence electrons in the atom.