Which of the following groups of elements are likely to be radioactive? actinides noble gases transition metals bcnos

actinides is your answer

hope this helps

Option (a) is the correct answer.

Explanation:

Transition metals are the metals whose valence electrons occupy 3d, 4d or 5d orbitals. Similarly, valence electrons of noble gases occupy the same energy shells as the transition metals.

Hence, nuclei of both transition and noble gases is not large enough. But the nuclei of actinides is large enough that it contains large number of protons and neutrons.

As a result, the atom becomes unstable and therefore, whenever actinides undergo spontaneous fission they releases large amount of energy.  

Hence, actinides are radioactive in nature.

Thus, we can conclude that actinides is the group of elements which are likely to be radioactive.