Question

Oxidation number of chromium in \[\text{Cr}{{\text{O}}_{\text{2}}}^{\text{2+}}\] is +6. If true enter 1,else 0.
A. 1
B. 0

Answer 1

Hint: Oxidation number of an element represents the number of electrons gained or lost by an atom of that element in the compound.
- Atoms lose or gain electrons to attain stable noble configuration.
- Sum of the oxidation number of all the elements is always equal to the total charge on the compound or complex.

Complete step by step answer:
- Our aim is to find the oxidation number of chromium in \[\text{Cr}{{\text{O}}_{\text{2}}}^{\text{2+}}\]
So, we can assume that the oxidation number of Cr in \[\text{Cr}{{\text{O}}_{\text{2}}}^{\text{2+}}\] be x.
- Next step is to see the net charge on the complex which is +2.
- Now we know that the total sum of oxidation states of all the elements in the given compound should be equal to 2.
- As we know that oxidation number of oxygen is 2, So adding all the oxidation numbers of all the elements present in the given complex and equating it equal to 2.
x+2(-2)=+2, therefore value of x =6.So, we can conclude that the oxidation number of chromium is +6.
- In the question it is given that if the oxidation number of chromium is +6 enter 1. So, our answer will be A.

Note: Always remember oxygen can opt 5 different oxidation States.
- In all the oxides it has oxidation state of -2
- In all peroxide it has oxidation state of -1
- In all superoxide it has oxidation state of $\dfrac{-1}{2}$
- In case of $\text{O}{{\text{F}}_{\text{2}}}$ it has oxidation state of +2
- There is ${{\text{O}}_{\text{2}}}{{\text{F}}_{\text{2}}}$ here to balance the -2 charge on 2F-atom each oxygen atom acquire a charge of +1.