Which of the following reagents can be used to distinguish between `SO_(2)` and `CO_(2)`?

Options

A. Lime water
B. Zinc nitroprusside paste in water
C. Potassium iodate and starch
D. Acidified potassium dichromate solution

Answer

B,C,D

Explanation

(B)Red colour compound of unknown composition is formed when moist `SO_2` is brought in contact with `Zn[Fe(CN)_5NO]` (salmon colour) paste in water.No colour change with `CO_2`.
(C )`5SO_2+2IO_3^(-)+4H_2O to I_2+5SO_4^(2-)+8H^(+) , I_2+` starch `to` blue colour.
No colour change observed with `CO_2`.
(D)`3SO_2+Cr_2O_7^(2-)+2H^(+)to2Cr^(3+)`(green solution) +`3SO_4^(2-) + H_2O`
No colour change is observed with `CO_2`