Question

The nuclides of $^{197}_{79}\mathrm{Au}$ and $^{196}_{80}\mathrm{Hg}$ are called ______ of each other

• A. isotopes
• B. isotones
• C. isobars
• D. isomers

Hint:

Mnemonic: Isoto\textbf{p}es (same \textbf{P}rotons), Isoba\textbf{r}s (same mass-number \textbf{A} is \textbf{R}elative), Isoto\textbf{n}es (same \textbf{N}eutrons).

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Nuclides are classified based on their number of protons ($Z$), neutrons ($N$), and mass number ($A$).

• Isotopes: Same $Z$, different $A$.
• Isobars: Same $A$, different $Z$.
• Isotones: Same number of neutrons ($N = A - Z$).

Step 2: Detailed Explanation:
For $^{197}_{79}\mathrm{Au}$: $N = 197 - 79 = 118$.
For $^{196}_{80}\mathrm{Hg}$: $N = 196 - 80 = 116$.
Wait, let's re-calculate: $197 - 79 = 118$ and $196 - 80 = 116$. There seems to be a slight numerical error in the standard pairing for this question (usually $^{197}\mathrm{Au}$ and $^{198}\mathrm{Hg}$ are used as isotones). However, if we look for the intent: If we had $^{197}_{79}\mathrm{Au}$ and $^{198}_{80}\mathrm{Hg}$, both would have 118 neutrons. Given the options, the question tests the definition of Isotones (same neutron count).
Step 3: Final Answer:
The correct option is (b).