Answer:
a
Explanation:
because of potassium and lithium belongs to
alkali metals
Answer:
Valence electrons. they can be used to determine the group of an element.
Explanation:
..............................
Element and compound , and or heterogeneous and homogeneous
Hydrogen-
Hydrogen is the answer because the number of protons is the atomic number. All the elements have different atomic numbers and hydrogen has the least with an atomic number of 1.