Structures of which of the following have coordinate bond in them
(i) `NO _(3) ^(-)` (ii) `O _(3)` (iii) `R-NC` (iv)`CO`

Explanation

To determine which of the given structures have coordinate bonds, we need to analyze each compound one by one. A coordinate bond (or dative bond) is formed when one atom donates both electrons to a bond, while the other atom does not contribute any electrons.

### Step-by-Step Solution:

1. **Analyze `NO3^(-)` (Nitrate Ion)**:
- The nitrate ion consists of one nitrogen atom bonded to three oxygen atoms.
- Nitrogen has five valence electrons, and each oxygen has six. In the nitrate ion, one of the oxygen atoms forms a double bond with nitrogen, while the other two oxygen atoms are bonded through single bonds.
- The oxygen that forms a single bond with nitrogen can donate a lone pair to nitrogen, resulting in a coordinate bond.
...