Which of the following gas turns potassium iodide and starch solution Blue?

H_{2} S

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H C l

gas

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H B r

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{N O}_{2}

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Solution

The correct option is D ${N O}_{2}$
$4 N O_{2} + 2 K I ⟶ 2 K N O_{3} + I_{2} + 2 N O$
When $N O_{2}$ reacts with $p o t a s s i u m$ iodide i.e. $K I,$ it leads to the formation of $I_{2}$ which is responsible for turning it blue.
Similarly, starch solution , when it reacts with $N O_{2},$ it forms $i o d i n e$ $(I_{2})$ which leads to its blue coloration.

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Which of the following gas turns potassium iodide and starch solution Blue?

The correct option is D NO24NO2+2KI⟶2KNO3+I2+2NOWhen NO2 reacts with potassium iodide i.e. KI, it leads to the formation of I2 which is responsible for turning it blue.Similarly, starch solution , when it reacts with NO2, it forms iodine (I2)which leads to its blue coloration.