Question

Match List-I with list-II: Name of Oxo acid, the Oxidation state of ‘P’.

List-IName of Oxo acid	List-IIThe oxidation state of ‘P’
(a)	Hypophosphorus acid	(i) \[ + 5\]
(b)	Orthophosphoric acid	(ii) \[ + 4\]
(c)	Hypophosphoric acid	(iii) \[ + 3\]
(d)	Orthophosphorus acid	(iv) \[ + 2\]
-	-	(v) \[ + 1\]

Choose the correct answer from the options given below:
1. \[(a) - (iv),(b) - (v),(c) - (ii),(d) - (iii)\]
2. \[(a) - (v),(b) - (iv),(c) - (ii),(d) - (iii)\]
3. \[(a) - (v),(b) - (i),(c) - (ii),(d) - (iii)\]
4. \[(a) - (iv),(b) - (i),(c) - (ii),(d) - (iii)\]

Answer 1

Hint: Oxidation states simplify the work of determining what is oxidised and what is reduced in redox reactions. A positive number results in an electron being lost, while a negative number results in an electron being gained.

Complete Step by Step Solution:
1. Oxidation state: An oxidation number indicates the oxidation state of an element within a compound according to a set of rules based on the assumption that electrons within a covalent bond belong entirely to the more electronegative element.
2. Oxidizing agent: A reagent that increases the oxidation number of an element in the compound is known as an oxidizing agent.
3. Reducing agent: A reagent that decreases the oxidation number of an element of the compound is known as a reducing agent.
4. The algebraic sum of the oxidation number of all atoms in a compound is equal to zero but for the polyatomic ions, the algebraic sum of all the oxidation numbers of all atoms of the ion is equal to the charge on the ion.
5. The oxidation number of Hydrogen and Oxygen is \[ + 1\,and\, - 2\].
6. The formula of Hypophosphorous acid is \[{H_3}P{O_2}\]and the calculation for oxidation number is expressed below:
Let us assume, the oxidation number of Phosphorus is x:
\[3 \times 1 + x + 2 \times \left( { - 2} \right) = 0\]
\[3 + x - 4 = 0\]
\[x - 1 = 0\]
\[x = + 1\]
7. The general formula of Orthophosphoric acid, Hypophosphoric acid, and Orthophosphorus acid is \[{H_3}P{O_4},{H_4}{P_2}{O_6},{H_3}P{O_3}\].
8. Similarly calculate the oxidation number of the other three Phosphorus compounds.
9. The oxidation number of Orthophosphoric acid, Hypophosphoric acid, and Orthophosphoric acid is \[ + 5, + 4, + 3\].
The correct option is c.

Additional information:
1. The oxidation number of Oxygen in Peroxides \[({H_2}{O_2},N{a_2}{O_2})\]is \[ - 1\]and in Super oxides \[\left( {K{O_2},Rb{O_2}} \right)\]is \[ - {\raise0.7ex\hbox{$1$} \!\mathord{\left/
 {\vphantom {1 2}}\right.\kern-\nulldelimiterspace}
\!\lower0.7ex\hbox{$2$}}\].
2. The oxidation number of Hydrogen is \[ - 1\] when it is attached to the metals in binary compounds \[(NaH,LiH)\].
3. The oxidation number of an atom in a free or uncombined state \[\left( {{H_2},{O_2},C{l_2}} \right)\]is zero.
4. Ions are composed of only one atom\[\left( {N{a^ + }} \right)\], the oxidation number equals the charge on the ion\[( + 1)\].

Note: An element that has a positive oxidation number is metallic, whereas an element that has a negative or positive oxidation number is non-metallic.