When triatomic gas `X_(3)` reacts with an excess of potassium iodide solution buffered with a borate buffer `(pH=9.2)` diatomic product `Y_(2)` is liberated which can be titrated agains a standard solution of sodium thiosulphate. This is a quantitative method for the estimation of `X_(3)` gas in the mxiture of `X_(3)` and `X_(2)` of some atom `X`.
`X_(2)` and `Y_(2)` are respectively?

Options

A. `Cl_(2)` and `I_(2)`
B. `O_(2)` and `I_(2)`
C. `N_(2)` and `I_(2)`
D. `O_(2)` and `H_(2)`

Answer

B

Explanation

`X_(2)=O_(2), X_(3)=O_(3), Y_(2)=l_(2)`
`2l^(-)+H_(2)O+O_(3) to 2OH^(-)+l_(2)+O_(2)`
`l_(2)+2S_(2)O_(3)^(2-)to2l^(-)+S_(4)O_(6)^(2-)`
`I_(2)+` Starch solution `to` Blue colouration
`I_(2)+I^(-)` (excess) `to` Brown coloured `I_(3)^(-)` ion
`O_(2)` is thermodynamically more stable as compred to `O_(3)`
`O_(3)` is pale blue gas which has characteristic smell`.