The oxidation state of `A, B`, and `C` in a compound are `+2, +5`, and `-2`, respectively. The compounds is

Options

A. `A_(2)(BC)_(2)`
B. `A_(2)(BC)_(3)`
C. `A_(3)(BC_(4))_(2)`
D. `A_(2)(BC_(4))_(3)`

Answer

C

Explanation

`A^(2+)B^(5+)C^(2-)`
Total positive charge `= 2x+5y`
Total negative charge `= 2z`
`:. 2x+5y= 2z`….(i)
`2x + 5y+ 2z =0`…..(ii)
Solving equations (i) , (ii), we get
`x=3, y=2, z=8`
Formula is `A_(3)B_(2)C_(8)=A_(3) (BC_(4))_(2)`
Alternatively: Check that the total charge shold be zero.
a. `A_(2)(BC)_(2)=2xx2+2xx5-2xx2`
`=10` (not zero)
b. `A_(2)(BC)_(3)=2xx2+3xx5-2xx3`
`= 13` (not zero)
c. `A_(3)(BC_(4))_(2)=2xx3+2xx5-2xx8`
`=0`
d.`A_(2)(BC_(4))_(3)=2xx2+3xx5-2xx12`
`-5` (not zero).