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This is one of our many quizzes on Oxidation numbers. Click on this to access more such competitive quizzes on Redox Reactions.

Oxidation numbers Quiz 2

chemistry

 ${{[Fe{{(CN)}_{6}}]}^{3-}}$ is an octahedral complex. What will be the overall charge on this complex to find the oxidation state of iron?

 The overall charge on the complex is written on the superscript of the octahedral complex.

  The overall charge on the complex is written on the superscript of the octahedral complex. The given complex is ${{[Fe{{(CN)}_{6}}]}^{3-}}$ so, its overall charge is $-3$.

   There are two compounds of nitrogen given below. What is the oxidation state of nitrogen in them: $ \\ N{{H}_{3}}$ and $N{{F}_{3}}$ 

  The oxidation number of hydrogen is taken +1 and the oxidation number of fluorine is -1 because it is a halogen.

 The oxidation number of nitrogen in $N{{H}_{3}}$ will be: $ \\ x+3(+1)=0\\ x+3=0\\ x=-3\\ $ The oxidation number of nitrogen in $N{{F}_{3}}$ will be: $ \\x+3(-1)=0 \\x-3=0 \\x=+3$ 

  We follow some rules when we find the oxidation state of the element in the compound. Which of the following is correct?

 The oxidation state of ${{N}_{2}}$, ${{O}_{2}}$, etc are 0, $N{{a}^{+}}$ is +1, ${{F}^{-}}$ is -1.

 From the given options, $(a)$ is correct because in the elemental state the element is alone and doesn’t have any charge on it. 

A compound is given below: <img src="https://cmds-vedantu.s3.ap-southeast-1.amazonaws.com/prod/question-sets/0f0a40f7-dd3c-43c6-b303-cc996c1fe5084948427062501213934.png"/> What are the oxidation states of Mn?

 The oxidation state can be found by the number of bonds formed by the manganese atoms.

 We can find the oxidation number by looking at the number of bonds made by the Manganese atoms. There are three manganese atoms in this structure. Two manganese atoms have three bonds, so their oxidation state will be +3, and one manganese atom has two bonds, so its oxidation state will be +2.

You are given a reaction: ${{H}_{2}}S+HN{{O}_{3}}\to NO+S+{{H}_{2}}O$ What is the change in the oxidation state of S?

 The oxidation state of Hydrogen is +1 and on the product side, sulfur is an elemental state.

$ \text{The oxidation state of S in }{{H}_{2}}S \text{will be:}\\ (+1)2+x=0\\ x+2=0 \\ x=-2 \\ \text{On the product side, the sulfur is in an elemental state and doesn't have any charge so, its oxidation}\\ \text{state will be 0}.$