Question

A mixture of salts `(Na_(2)SO_(3)+K_(2)Cr_(2)O_(7))` in a test tube is treated with dil. `H_(2)SO_(4)` and resulting gas is passed through lime-water. Which of the following observations is correct about this test
A. Solution in test tube becomes green and lime-water turns milky
B. Solution in test tube is colourless and lime-water turns milky
C. Solution in test becomes green and lime-water remains clear
D. Solution in test tube remains clear and lime-water also reamains clear.

Answer 1

Correct Answer - A
`Na_(2)SO_(3)` with dil. `H_(2)SO_(4)` produces `SO_(2)` gas which turns `K_(2)Cr_(2)O_(7)` and lime water into green and milky, respectively.
`Na_(2)SO_(3)+H_(2)SO_(4)toNa_(2)SO_(4)+H_(2)O+SO_(2)uarr`
`K_(2)Cr_(2)O_(7)+H_(2)SO_(4)+SO_(2)toK_(2)SO_(4)+Cr_(2)underset("green")((SO_(4)))_(3)+H_(2)O`
`Ca(OH)_(2)+SO_(2)tounderset("milky")(CaSO_(3))+H_(2)O`