8. (a) Tick (™) the box next to the correct statement about the mixture.
mixture of four elements
mixture of four compounds
mixture of two elements and two compounds
mixture of one element and three compounds​

mixture of four compounds

mixture of two elements and two compounds

Explanation:

what are the two models

explanation:

since the atomic number is the number of protons in the nucleus, as we move to the left on the periodic table, the electrostatic pull between the nucleus and the valence electron shell decreases. as we move down a group (vertical column), the valence shell energy level gets further and further from the nucleus.