Q. Ether in contact with air for a long time form peroxides. The presence of peroxide in either can be tested by adding $Fe^{2 +}$ ion and then adding
A) $KCN$
B) $SnCl_{2}$
C) $HgCl_{2}$
D) $KCNS$
Explanation
(d)
Peroxide will oxidise $Fe^{2 +}$ to$\ Fe^{3 +}\$which gives a blood red colour with KCNS.
$O_{2}^{2 -} + 2Fe^{2 +} + 4H^{+} \rightarrow 2Fe^{3 +} + 2H_{2}O$
$Fe^{3 +} + 3KCNS \rightarrow \ Fe(CNS)_{3}\ \ \ \ \ \ \ \ \ + 3K^{+}$
(blood red colour)
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.