Question

Which statement describes the periodic law?

Metals are both good conductors of heat and electricity.
Atomic masses always increase across a period.
Nonmetals are of the most reactive elements.
Elements in the same group have similar chemical properties.

Answer 1

elements is the same group have similar chemical properties

Answer 2

Answer is: elements in the same group have similar chemical properties.
Periodic law is the arrangement of the elements in order of increasing atomic number.
For example all alkaline metals (I group of periodic table, Na, K, Cs...) loose one electron in chemical reaction and react vigorously with water.