Question

Which of the following are isobars?

• A. $^{232}_{92}U$ and $^{238}_{92}U$
• B. $^2_1H$ and $^3_1H$
• C. $^3_1H$ and $^3_2He$
• D. $^{14}_7N$ and $^{15}_7N$

Hint:

Remember the definitions: Isotopes have the same atomic number ($Z$), Isobars have the same mass number ($A$), and Isotones have the same number of neutrons ($A-Z$).

Answer 1

The Correct Option is C

To determine which pair among the given options are isobars, we first need to understand the concept of isobars. 

Isobars are atoms that have the same mass number (A) but different atomic numbers (Z). In simple terms, isobars have the same total number of protons and neutrons, but they are different elements or different isotopes of elements.

1. \(^{232}_{92}U\) and \(^{238}_{92}U\):
   • Both have different mass numbers (232 and 238) and the same atomic number (92). They are isotopes, not isobars.
2. \(^2_1H\) and \(^3_1H\):
   • Both have different mass numbers (2 and 3) and the same atomic number (1). They are isotopes, not isobars.
3. \(^3_1H\) and \(^3_2He\):
   • Both have the same mass number (3), but different atomic numbers (1 and 2). They satisfy the criteria for isobars.
4. \(^{14}_7N\) and \(^{15}_7N\):
   • Both have different mass numbers (14 and 15) and the same atomic number (7). They are isotopes, not isobars.

Based on this analysis, the correct pair that are isobars is \(^3_1H\) and \(^3_2He\).