Composition check: the nucleus of uranium-235 (written as 92U235) contains how many protons?

Introduction / Context:
Nuclear notation A Z X helps decode fundamental properties: A is mass number (protons + neutrons), Z is atomic number (protons), and X is the chemical symbol. This is essential for balancing nuclear reactions and understanding isotopes.

Given Data / Assumptions:

• Isotope given: 92U235.
• Z (the atomic number) equals the number of protons.
• A (the mass number) equals protons + neutrons.

Concept / Approach:
For 92U235, Z = 92 indicates 92 protons. The mass number A = 235 means total nucleons are 235, so neutrons = A - Z = 235 - 92 = 143. Thus, “92” is the correct answer for the number of protons. This simple parsing skill is used in reaction equations, decay chains, and neutron economy assessments.

Step-by-Step Solution:
Identify Z from the isotope notation: Z = 92.Proton count equals Z, so protons = 92.Optional: compute neutrons = 235 - 92 = 143 for completeness.Select 92 as the number of protons.

Verification / Alternative check:
Periodic table confirms uranium’s atomic number is 92, matching the proton count in all uranium isotopes (mass numbers vary with neutron count).

Why Other Options Are Wrong:
235: Mass number, not proton count.143: Neutron count for U-235, not protons.325/126: Not related to U-235 proton number.

Common Pitfalls:
Mixing mass number with atomic number; always remember Z = protons, A = protons + neutrons.

Final Answer:
92