Question : Which radioactive element with atomic number 43 in the modern periodic table is unstable, and the half-lives of all its isotopes are relatively short, from 4.2 million years to 5.0 s?
Option 1: Nobelium
Option 2: Promethium
Option 3: Neptunium
Option 4: Technetium
Correct Answer: Technetium
Solution : The correct option is Technetium.
The radioactive element with atomic number 43 in the modern periodic table is Technetium (Tc). All its isotopes are unstable, and their half-lives range from 4.2 million years to 5.0 seconds. Due to their short half-lives, technetium isotopes are not found naturally in significant amounts on Earth.
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