Q.Give example of mirror nuclei.

Step 1. Mirror nuclei are defined as isobars (same mass number A) whose proton count and neutron count are interchanged and differ from each other by exactly 1.

Step 2. Hydrogen-3 (3-1-H) has 1 proton and 2 neutrons (N-Z = 1); helium-3 (3-2-He) has 2 protons and 1 neutron (Z-N = 1) -- same A=3, with the proton/neutron counts of one being the neutron/proton counts of the other, and differing by 1. This is a mirror-nuclei pair.

Step 3. A second example given in this chapter: carbon-13 (13-6-C, 6 protons + 7 neutrons) and nitrogen-13 (13-7-N, 7 protons + 6 neutrons) -- again same A=13, counts swapped, differing by 1.

Recall the definition of mirror nuclei (same-A isobars with proton/neutron counts swapped, differing by 1) and give a matching example pair from the chapter.

• Confusing mirror nuclei with isotones or plain isobars, which do not require the swapped-and-differ-by-1 condition.
• Picking a pair that does not actually share the same mass number A.