Ethylene diaminetetraacetate (EDTA) ion is:

The stabilization of coordination compounds due to chelation is called the chelate effect. Which of the following is the most stable complex species?

Which of the following species is not expected to be a ligand?

1. NO

2. NH${}_4^{+}$

3. ${\mathrm{NH}}_2{\mathrm{CH}}_2{\mathrm{CH}}_2{\mathrm{NH}}_2$

4. CO

The correct order of increasing field strength of ligands is:

1. ${\mathrm{SCN}}^{- }< {\mathrm{F}}^{- }< {\mathrm{CN}}^{- }< {\mathrm{C}}_2{\mathrm{O}}_4^{2-}$

2. ${\mathrm{F}}^{- }< {\mathrm{SCN}}^{- }< {\mathrm{C}}_2{\mathrm{O}}_4^{2- }< {\mathrm{CN}}^{-}$

3. ${\mathrm{CN}}^{- }< {\mathrm{C}}_2{\mathrm{O}}_4^{2- }< {\mathrm{SCN}}^{- }< {\mathrm{F}}^{-}$

4. ${\mathrm{SCN}}^{- }< {\mathrm{F}}^{- }< {\mathrm{C}}_2{\mathrm{O}}_4^{2- }< {\mathrm{CN}}^{-}$

The ligand(s)that show a chelating effect is/are:

Match Column-I with Column-II and mark the correct option.

Codes:
1. i=d, ii=c, iii=b, iv=a

2. i=c, ii=d, iii=b, iv=a

3. i=c, ii=d, iii=a, iv=b

4. i=a, ii=c, iii=b, iv=d