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

photosynthesis makes the glucose that is used in cellular respiration to make atp. the glucose is then turned back into carbon dioxide, which is used in photosynthesis. while water is broken down to form oxygen during photosynthesis, in cellular respiration oxygen is combined with hydrogen to form water.