Atom X has 17 protons. How many electrons are in its valence shell (outermost energy level)? A. 7
B.3
C.5
D.10

Atom C has 17 protons, and since it is stated in the question that it's an atom, not an ion so it will have same number of electrons as protons, so that the atom will be electrically neutral.

now,

since, last shell is M shell... So, number of electrons in its valence shell (outermost energy level) is 7 electrons

evidence and logical support is essential for a scientist to do in order to maintain credibility. this is because no one can believe without any logic and without any evidence.hence a scientist can maintain credibility by proving himself and by answering logically so experiments prove very beneficial. logical hypothesis give conclusion which is acceptable. therefore, there are two main factors to maintain credibility by a scientist is evidence and logical support.