1. Hydrogen has one electron of valence, it means that the covalent bond formed will be:
2. Fluorine has 7 electrons of valence:
3. Oxygen has 6 electrons of valence, it forms 2 covalent bonds:
4. Nitrogen has 5 electrons of valence, it forms 3 covalent bonds:
5. Carbon has 4 electrons of valence and oxygen has 6. They form 4 covalent bonds this way: