The equal mass indicates that both atoms have the same number of protons and neutrons.
A positive charge signifies a difference in electron count.
Assuming the atomic number is A,
the mass number equals M.
In a neutral atom, there are A electrons.
A negatively charged atom would have A + 1 electrons [while the count of protons and mass number remains unchanged].
A positively charged atom contains A - 1 electrons [with consistent protons and mass number].
For instance: Cl- and Cl+.
The true statement is B. With identical masses for both metals, the final temperature of the two will be more aligned with 498 K rather than 298 K, as iron's specific heat capacity is significantly greater than that of gold's.