A certain compound`(X)` when treated with copper sulphate solution yields a brown precipatate ,On adding hypo solution ,the ppt ,turns white.The compound `(X)` is

Options

A. `K_(3)PO_(4)`
B. `KI`
C. `KBr`
D. `K_(2)CO_(3)`

Answer

2

Explanation

when we add potassium iodide solution to copper sulphate brown coloured `I_(2)` is obtained:
`CuSO_(4)+2KlrarrCu l_(2)+K_(2)SO_(4)`
`2Cu l_(2)rarrCu_(2)l_(2)+I_(2)`
Iodine is decolourised by sodium thiosulphate (hypo) where white ppt of sodium tetrathionate is formed:
`2Na_(2)S_(2)O_(3)+I_(2)rarr2Nal+Na_(2)S_(4)O_(6)`