(i) Write the products formed in the reaction of concentrated nitric acid with zinc.
(ii) d-block elements readily form complexes. Give reason.

Explanation

(i) Zinc with Conc. `HNO_(3): 4Zn+10HNO_(3) to underset(("Zinc nitrate"))(4Zn(NO_(3))_(2))+underset(("Ammonium nitrate"))(NH_(4)NO_(3))+3H_(2)O`
(ii) 1. Transition elements (d-block elements ) have a tendency to form coordination compounds (complexes) with a species that has an ability to donate an electron pair to form a coordinate covalent bond.
2. Transition metal ions are small and highly charged and they have vacant low energy orbitals to accept an electron pair donated by other groups. Due to these properties, transition metals form large number of complexes.
3. Examples: `[Fe(CN)_(6)]^(4-), [Co(NH_(3))_(6)]^(3+)`