A mixture of salts $({N a}_{2} {S O}_{3} + K_{2} {C r}_{2} O_{7})$ in a test tube is treated with $d i l . H_{2} {S O}_{4}$ and resulting gas is passed through lime water. Which of the following observations is correct about this test?

Solution in test tube becomes green and line water turns milky

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Solution in test tube is colourless and lime water turns milky

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Solution in test tube becomes green and line water remains clear

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Solution in test tube remains clear and lime water also remains clear

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Solution

The correct option is A Solution in test tube becomes green and line water turns milky
Reactions taking place inside the test tube
(i) ${N a}_{2} {S O}_{3} + H_{2} {S O}_{4} ⟶ {N a}_{2} {S O}_{4} + H_{2} O + {S O}_{2}$
(ii) $K_{2} {C r}_{2} O_{7} + 3 {N a}_{2} {S O}_{3} + 4 H_{2} {S O}_{4} ⟶ 2 {N a}_{2} {S O}_{4} + K_{2} {S O}_{4} + {C r}_{2} {({S O}_{4})}_{3} + 4 H_{2} O$
(iii) $C a {(O H)}_{2} + {S O}_{2} ⟶ C a {S O}_{3} ↓ + H_{2} O$

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