Question

Which pair is correctly matched ? 1)[Fe(OH)3]:Fe3+ 2)[As2S3]:As3+ 3)[SnO2]:SnO2−3:in acidic medium 4)[Agl]:I−in excess of AgNO3 best explanation=brainliest

Answer 1

Explanation:

Iron (III) nitrate and potassium thiocyanate react to give deep red coloration.

The reaction is:

Fe

aq

3+

+SCN

−

↔[FeSCN]

aq

2+

yellow deep red

Now, to this solution, if oxalic acid (H

2

C

2

O

4

) is added, then it reacts with Fe 3+ ions to form the stable complex ion [Fe(C 2 O 4 ) 3 ] 3− , thus decreasing the concentration of Fe

3+ ions. In accordance with the Le-Chatelier's principle, the decrease in the concentration of Fe

3+

ions, leads to the decrease in the concentration of [FeSCN]

2+

ions which is indicated by the fact that the colour of the solution becomes lighter.