Question

$A$ and $B$ are isotopes. $B$ and $C$ are isobars. All three are radioactive.

• A. $A$, $B$ and $C$ must belong to the same element
• B. $A$, $B$ and $C$ may belong to the same element
• C. It is possible that $A$ will change to $B$ through a radio-active-decay process
• D. It is possible that $B$ will change to $C$ through a radio-active -decay process

Answer 1

Answer: (D)

It is possible that $B$ will change to $C$ through a radio-active -decay process

Isotopes
The number of nucleons (both protons and neutrons) in the nucleus is the atom's mass number, and each isotope of a given element has a different mass number. For example, carbon-12, carbon-13 and carbon-14 are three isotopes of the element carbon with mass numbers 12, 13 and 14 respectively.
(A and B)
Isobars
Isobars are atoms (nuclides) of different chemical elements that have the same number of nucleons. Correspondingly, isobars differ in atomic number (or number of protons) but have the same mass number.
(B and C)
Clearly By definition, A,B and C cannot be same element
also since A and B are same elements, A cannot convert to B by any radioactive process.