In the electron configuration [ar]4s23d104p4, which are valence electrons?

The valence electrons are the one in the subshells 4s and 4p.

Explanation:

Let's consider the following electron configuration.

[Ar] 4s² 3d¹⁰ 4p⁴

The valence electrons are the ones in the last level, that is, the level 4. Here, there are two electrons in the s subshell and four electrons in the p subshell. In total, there are 2 + 4 = 6 valence electrons.

2,10,4 are valence electrons