`SO_(2)` and `CO_(2)` both turn lime water `(X)` milky, `SO_(2)` also turns `K_(2)Cr_(2)O_(7)//H^(+) (Y)` green while `O_(2)` is soluble in pyrogallol `(Z)` turning it black. These gases are to be detected in order by using these reagents. The order is:

Options

A. (X),(Y),(Z)
B. (Y),(X),(Z)
C. (X),(Z),(Y)
D. The correct order cannot be predicted.

Answer

B

Explanation

(i)`Cr_(2)O_(7)^(2-)+3SO_(2)+2H^(+)to2Cr^(3+) ("green")+3SO_(4)^(2-)+H_(2)O,CO_(2)` and `O_(2)` do not give reactions with acidified `K_(2)Cr_(2)O_(7)`
(ii)`Ca(OH)_(2)+CO_(2)toCaCO_(3)darr ("white") +H_(2)O,O_(2)` does not give reaction with acidified `K_(2)Cr_(2)O_(7)`
(iii)`O_(2)` dissolves in pyragallol.