Answer:
The correct answer is - ascending order of atomic numbers in period and similar characters in groups.
Explanation:
The modern periodic table is arranged in periods and groups. In periods the arrangement of the elements are on the basis of the increasing order of atomic numbers.
In groups of the periodic table, elements are arranged on the basis of the similar characters of the elements and number of electrons in outer shell of the elements. The elements in the Modern Periodic Table are arranged in 7 Periods and 18 Groups.
Thus, the correct answer is - ascending order of atomic numbers in period and similar characters in groups.
