Answer
K and Na
F and Cl
P and N
Work Step by Step
K (potassium) and Na (sodium) are in the same column on the periodic table, group 1A (the alkali metals), so we can assume that their chemical properties will be similar.
F (fluorine) and Cl (chlorine) are in the same column on the periodic table, group 7A (the halogens), so we can assume that their chemical properties will be similar.
P (phosphorus) and N (nitrogen) are in the same column on the periodic table, group 5A, so we can assume that their chemical properties will be similar.
