Energy levels inside an atom are the specific energies that electrons can have when energy occupies specific orbitals. Electrons can be excited to higher energy levels by absorbing energy from the surroundings, an equivalent light is emitted when an electron returns from a high energy state to a lower one. Representation of this diagrammatic is known as the energy level diagram.
The atomic number (Z) uniquely identifies a chemical element. In an uncharged atom, the atomic number is also equal to the number of electrons.
The atomic number, Z, should not be confused with the mass number, A, which is the number of nucleons, the total number of protons and neutrons in the nucleus of an atom.
In this video Kristine Born explains this two concepts in more detail.
Answer:
Carbon dioxide is a linear covalent molecule.
Carbon dioxide is an acidic oxide and reacts with water to give carbonic acid.
CO 2 + H2O ==> H2CO3
Carbon dioxide reacts with alkalis to give carbonates and bicarbonates.
CO 2 + NaOH ==> NaHCO3 (Sodium BiCarbonate )
NaHCO3 + NaOH ==> Na2CO3 (Sodium Carbonate) + H2O