You need to prepare 100.0 ml of a ph=4.00 get the buffer solution using 0.100 m benzoic acid (pka = 4.20) and 0.140 m sodium benzoate.

each chemical family is represented as a group or column on the periodic table. based on chemical properties, there are 6 types of chemical families. group 1 represents alkali metals, group 2 represents alkaline earth metals, groups 3 to 12 represent transition metals, groups 13 to 16 represent non-metals and other metals, group 17 represents halogens and group 18 represents noble gases.