Question

The number of elements in the 4th period of periodic table are -

• A. 8
• B. 18
• C. 10
• D. 32

Answer 1

The correct option is B

18

Explanation:

• There are seven periods in the long form of the periodic table. The elements of the same period have the same number of energy levels or shells but different valence electrons.
• The elements whose valence electrons enter in the 4th shell or energy level belong to the 4th period. There are 18 elements in the 4th period of the modern period table.
• The elements of period 4 include Potassium (K), Calcium (Ca), Scandium (Sc), Titanium (Ti), Vanadium (V), Chromium (Cr), Manganese (Mn), Iron (Fe), Cobalt (Co), Nickel (Ni), Copper (Cu), Zinc (Zn), Gallium (Ga), Germanium (Ge), Arsenic (As), Selenium (Se), Bromine (Br), Krypton (Kr).

Therefore, the correct option is (B) i.e. 18.