What was the main use of constellations in ancient times?
o locate specific stars
O help navigate at night
O determine magnitude of stars
O predict time of the year

the ans is option b(help navigate at night)

that tool would be a compass

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.