Which of the following ions forms most stable complex compound?
Cu2+
Ni2+
Fe2+
Mn2+
A.
Cu2+
The transition elements form complexes because of the following reasons-
(i) They have small size.
(ii) They have large effective nuclear charge.
(iii) They have vacant d-orbitals so that these orbitals can accept lone pairs of electrons donated by the ligands.
Cu2+ has smallest size and highest nuclear charge among the given species. Hence, it forms the most stable complex compound.
Pb2+, Cu2+, Zn2+ and Ni2+ ions are present in a given acidic solution. On passing hydrogen sulphide gas through this solution the available precipitate will contain
PbS and NiS
PbS and CuS
CuS and ZnS
CuS and NiS
To an acid solution of an anion a few drops of KMnO4 solution are added. Which of the following, if present will not decolourise the KMnO4 soltuion?
NO
S2-
Cl-
CO
Which of the following complex neutralises three molecules of AgNO3?
[Co(NH3)6]Cl3
[Co(NH3)5Cl]Cl2
[Co(NH3)4Cl2]Cl
[Co(NH3)3Cl3]
Elements which generally exhibit multiple oxidation states and whose ions are usually coloured are
metalloids
non- metals
tranistion elements
gases
The transition metals mostly are
diamagnetic
paramagentic
neither diamagnetic nor paramagnetic
both diamagnetic and paramagnetic.
The correct statement in respect of d-block elements is
they are all metals
they show variable valency
they form coloured ions and complex salts
All the above statements are correct
On reduction of KMnO4, by oxalic acid in acidic medium, the oxidation number of Mn changes. What is the magnitude of this change?
From 7 to 2
From 6 to 2
From 5 to 2
From 7 to 4