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Q.
What is the oxidation number of vanadium in $R b_{4} N a\left[H V_{10} O_{28}\right] ?$
AMUAMU 2014Redox Reactions
Solution:
$R b_{4} N a\left[H V_{10} O_{28}\right]$
Let oxidation number of $V$ is $x$.
$\therefore 4 \times 1+1+[+1+10 x+28(-2)]=0$
or $4+1+1+10 x-56=0$
or $x=+5$