Question

Chlorine is in +1 oxidation state in:
A.HCl
B.$HCl{O_4}$
C.Both Option A & B
D.None of these

Answer 1

Oxidation state is also called the Oxidation number. Basically oxidation number is the total number of electrons that an atom either gains or loses in order to form a chemical bond with another atom.

Complete step by step answer:
1. Chlorine has many oxidation states and mostly all the oxidation states are stable. Generally chlorine is an electronegative atom so it shows negative oxidation state. But in some cases, it also shows Positive Oxidation state to form stable compounds.
2. In this question, in the first option HCL, CL atom is more electronegative than H atom. Since H & CL both have one valency. So ${{\text{H}}^ + }$ exist and ${\text{C}}{{\text{l}}^ - }$ exist as ion forms. In HCl, Cl atom is in -1 oxidation state.
3. In second option, $HCl{O_4}$
$HCl{O_4}$is a strong acid. This is an oxyacid of chlorine. H is always in +1 oxidation state. O is in -2 Oxidation state.
Let Cl is in an oxidation state. Sum of all the oxidation numbers of atoms in a compound should be zero. $HCl{O_4}$
→ $+ 1 + x + \left( { - 2} \right) \times {\text{ }}4{\text{ }} = {\text{ }}0$
→ $x{\text{ }}-{\text{ }}7{\text{ }} = {\text{ }}0$
→$\;x{\text{ }} = {\text{ }}7$
CL has +7 oxidation states in $HCl{O_4}$
In Spite of being electronegative atom CL shows positive oxidation state in oxyacids. Among these options Option D is correct.
In HCl , $HCl{O_4}$ Both, Cl is not in +1 Oxidation state.
Chlorine is present in 17 groups and the 4th period of the periodic table.
In the periodic table, Only P block elements show variable oxidation states. While S block, F block have fixed oxidation states.

Note:
Chlorine is also a P block element. It shows variable oxidation states. That is -1, +1, +3, +5, +7 all oxidation numbers are stable.
Oxidation state of chlorine is different with different atoms. But with S block and D block, Cl always shows negative oxidation state. It shows a positive oxidation state with P block elements. Maximum positive oxidation that chlorine shows is +7. Most stable oxidation shown by chlorine is -1.