The correct classification of H₂O, B₂H₆, and NaH respectively is-

1. Covalent, Covalent, & Covalent.

2. Covalent, Covalent, & Ionic.

3. Covalent, Ionic, & Covalent.

4. Interstitial, Covalent, & Covalent.

The freezing point of heavy water in comparison to normal water is -

1. Higher 

2. Lower 

3. Same

4. None of the above