If you have not already done so, download Avogadro for free and watch the tutorials if necessary.
Using the Lewis electron-point method, build the carbonic acid molecule in your notebook.
Now, check what type of hybridization the molecule has.
Import the same molecule with Avogadro and check the properties:
• the required molecular formula and structural formula are correct;
• the hybridization chosen is correct by looking for it in the properties of the bond angles;
• Hybridization doesn’t change if you build sodium carbonate, but is different? What did you do to switch from the carbonic acid molecule to the sodium carbonate molecule? Describe all the bonds present.