Final answer:
The atom with the given electron configuration 4d10 5s0 has 10 valence electrons, all of which are present in the 4d subshell. The 5s subshell is noted but contains no electrons.
Step-by-step explanation:
To determine the number of valence electrons in an atom with the electron configuration 4d105s0, we need to identify the outermost energy level that contains electrons. The electron configuration specified does not adhere to the standard notation since the 5s subshell should typically be filled before the 4d, but considering the information given, we can conclude that the valence electrons are the electrons in the highest energy level, including both the s and d subshells when applicable.
For an atom represented by 4d105s0, the valence shell is the fifth shell due to the presence of the 5s subshell; despite it being empty, it indicates that the valence shell is n=5. As such, the valence electrons are those in the 4d subshell, amounting to 10 electrons. However, since there are no electrons in the 5s subshell, the total number of valence electrons is 10. It is noteworthy that, typically, the 5s subshell would be filled before the 4d, but based on the provided configuration, we follow the given sequence to determine the valence electrons.