I would think the last one about the ozone layer
a covalent bond and an ionic bond. An ionic bond if formed from the transfer of electrons from the outer shell of atoms. ... An example of this is NaCl, where the sodium atom becomes Na+ due to the loss of electrons, and the chlorine atom becomes the negatively charged chloride (Cl-).
Water has a density of 1 g/cc. If you have 1 cc of water, then the mass it contains would be 1 g. <span>Density is a physical
property of a substance that represents the mass of that substance per unit
volume. It is a property that can be used to describe a substance. Hope this answers the question. Have a nice day.</span>
A covalent bond would happen