Question

All radioactive elements are present in which of the following:

विकल्प

• 3d series

• 4d series

• Actinoid series

• Lanthanoid series

Answer 1

Actinoid series

Explanation:

The Actinoid series (also known as Actinides) consists of 15 chemical elements with atomic numbers ranging from 89 (Actinium) to 103 (Lawrencium). All elements in this series are radioactive because they have unstable atomic nuclei that undergo radioactive decay. While some elements like uranium and thorium occur naturally, most are synthetic (man-made).