Elements in the Modern Periodic Table are arranged in _____________ vertical columns called groups and ______________ horizontal rows called periods.

Correct option is A

The correct answer is (a) 18, 7.
In the Modern Periodic Table, elements are organized into 18 vertical columns called groups and 7 horizontal rows called periods:
· Groups (18): Elements in the same group share similar chemical properties because they have the same number of valence electrons. The groups are numbered from 1 to 18.
· Periods (7): Elements in the same period have the same number of electron shells, and the period numbers range from 1 to 7.
Information Booster:
· The arrangement of elements in the periodic table is based on their atomic number.
· This layout follows the principles of the Periodic Law, which states that the properties of elements recur periodically when arranged by increasing atomic number.
· The 18 groups include main group elements, transition metals, and noble gases.
· The 7 periods vary in the number of elements they contain, with the first period having 2 elements and the others having progressively more.