Question

The atomic number of cobalt is $27$. The $EAN$ of cobalt in $Na_3 [Co(NO_2)_4Cl_2]$ is

• A. 35
• B. 24
• C. 36
• D. 34

Answer 1

Answer: (C)

36

Answer 2

EAN of $Co$ in $Na _{3}\left[ Co \left( NO _{2}\right)_{4} Cl _{2}\right]$
$=$ Atomic number of Co \pm oxidation state of Co

$+$ number of $e^{-}$ taken from $- NO _{2}$ and $- Cl$
$=27+3+(4+2)=36$