QJEEAdv18Chb2a7: JEE Advanced 2018 Chemistry - Class 12 JEEAdv18Chb2a7 Solution: The correct option(s) to distinguish nitrate salts of and taken …
Multiple Choice Options
- A shows the characteristic green color in the flame test
- B Only shows the formation of precipitate by passing in acidic medium
- C Only shows the formation of precipitate by passing in faintly basic medium
- D has higher reduction potential than (measured under similar conditions)
Step-by-Step Verified Solution
Statement wise explanation is
Statement (a) Mn2+ produces yellow-green colour in flame test while Cu2+ produces bluish-green colour in flame test. Thus, due to the presence of green colour in both the cases, flame test is not the suitable method to distinguish between nitrate salts of Cu2+ and Mn2+. Hence this statement is wrong.
Statement (b) Cu2+ belong to group II of cationic or basic radicals. It gives black ppt. of CuS if H2S is passed through it in the presence of acid (e.g. HCl). Mn2+ does not show this property hence this can be considered as a suitable method to distinguish between Mn2+ and Cu2+. Hence, this statement is correct.
Statement (c) In faintly basic medium when H2S is passed both Cu2+ and Mn2+ forms precipitates. Thus, it is not suitable method to distinguish between them. Hence, this statement is incorrect.
Statement (d) The standard reduction potential of Cu2+ /Cu is +0.34 V while that of Mn2+/Mn is 1.18 V. This can be used to distinguish between Cu2+ and Mn2+. In general less electropositive metals have higher SRP. Hence, this statement is correct.