The dand fblock elements - Result Question 49
####49. Acidified $K_2 Cr_2 O_7$ solution turns green when $Na_2 SO_3$ is added to it. This is due to the formation of:
(a) $Cr_2(SO_4)_3$
(b) $CrO_4{ }^{2-}$
(c) $Cr_2(SO_3)_3$
(d) $CrSO_4$
[2011]
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Solution:
- (a) The green colour appears due to the formation of $Cr^{3+}$ ion
$Cr_2 O_7^{2-}+3 SO_3^{2-}+8 H^{+} \longrightarrow 3 SO_4^{2-}+2 Cr^{3+}+4 H_2 O$
