Interpreting the nuclide symbol ²⁰⁹Bi

Steps:

• Bismuth (Bi) has atomic number Z=83, so a neutral atom has 83 electrons (statement 1 correct).
• Mass number A=209, so neutrons N=A-Z=209-83=126 (statement 2 correct).
• Nucleons are total protons + neutrons = A=209, not 126 (statement 3 incorrect).

Why B is correct:

• It includes verified statements 1 and 2 based on atomic number and mass number definitions.

Why the others are wrong:

• A omits correct statement 2.
• C includes incorrect statement 3 and omits statement 1.
• D includes incorrect statement 3.

Final answer: B