Question

what is the oxidation state of [co (nh3)6]3+

Answer 1

x+(0)6=+3
then X=+3 Is o state of Co.

Answer 2

Answer : The oxidation state of Co is, (+3)

Explanation :

Rules for Oxidation Numbers :

• The oxidation number of a free element is always zero.
• The oxidation number of a monatomic ion equals the charge of the ion.
• The oxidation number of  Hydrogen (H)  is +1, but it is -1 in when combined with less electronegative elements.
• The oxidation number of  oxygen (O)  in compounds is usually -2, but it is -1 in peroxides.  
• The oxidation number of a Group 1 element in a compound is +1.  
• The oxidation number of a Group 2 element in a compound is +2.  
• The oxidation number of a Group 17 element in a binary compound is -1.
• The sum of the oxidation numbers of all of the atoms in a neutral compound is zero.
• The sum of the oxidation numbers in a polyatomic ion is equal to the charge of the ion.

The given coordination compound is, $[Co(NH_3)_6]^{3+}$

Let the oxidation state of Co be, 'x'

$x+6(0)=+3\\\\x=+3$

Hence, the oxidation state of Co is, (+3)