Choose the correct tests with respective observations. Choose the correct answer from the options given below :
- A, D and E only
- A, B and C only
- B, D and E only
- C, D and E only
Answer
(2) A, B and C only
Solution
A: 2Cu2+ + [Fe(CN)6]4- Cu2[Fe(CN)6], a chocolate brown precipitate (confirmatory test of Cu2+) correct.
B: 4Fe3+ + 3[Fe(CN)6]4- Fe4[Fe(CN)6]3, Prussian blue precipitate (test of Fe3+) correct.
C: 2Zn2+ + [Fe(CN)6]4- Zn2[Fe(CN)6], white or bluish white precipitate (test of Zn2+) correct.
D: Mg2+ is not tested with potassium ferrocyanide and gives no blue precipitate (it is confirmed with disodium hydrogen phosphate / magneson reagent) incorrect.
E: Ba2+ gives no white precipitate with potassium ferrocyanide (it is confirmed as yellow BaCrO4 with potassium chromate) incorrect.
A, B and C only are correct.
Answer: (2)