Atoms

ln fluorescence, emission of light stops as soon as incidence of light stops.

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

• Isotopes: Same , different .
• Isobars: Same , different .
• Isotones: Same number of neutrons ( ).

Step 2: Detailed Explanation:
For : .
For : .
Wait, let's re-calculate: and . There seems to be a slight numerical error in the standard pairing for this question (usually and are used as isotones). However, if we look for the intent: If we had and , 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).