pBlock ElementsII - Result Question 129
####14. Concentrated nitric acid upon long standing, turns yellow-brown due to the formation of
(2013 Main)
(a) $NO$
(b) $NO _2$
(c) $N _2 O$
(d) $N _2 O _4$
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Solution:
- $NO _2$ is a brown coloured gas and imparts this colour to concentrated $HNO _3$ during long standing.
$$ 4 HNO _3 \longrightarrow 2 H _2 O+2 NO _2+3 O _2 $$
