A naturally occurring element, X, has atomic number 29 and exists in two stable isotopic forms. One isotope contains 33 neutrons and accounts for 25.0\% of naturally occurring atoms, while the other isotope contains 35 neutrons and accounts for the remaining 75.0\%.
Answer the following questions, showing all calculations and clearly stating your reasoning.
(a) Write the complete nuclear symbol (mass number, atomic number, and chemical symbol) for each isotope of element X.
(b) Calculate the average atomic mass of element X, expressed to four significant figures. Assume the mass of each isotope in atomic mass units (u) equals its mass number.
(c) Explain why the calculated average atomic mass may differ slightly from the value reported on a high-precision periodic table.