16) According to the Activity Series chemistry reference table, which of these metals will react most readily with 1.0 M HCl to produce H2(g)?
1) Zn
2) Mg
3) Ca
4) K

The correct answer is (1). Zn has the highest electronegativity of all the metals in its column. It has a strong attraction for electrons and low ionization potential, so if potassium chloride were used instead of hydrochloric acid, potassium would react most readily.

Explanation:

This question is asking which metal will react most readily. According to the activity series, alkali metals are more reactive than alkaline earth metals. Magnesium has the lowest outer electron configuration of all the metals in its row on the periodic table so it will have a strong attraction for electrons. The magnesium atom therefore requires less energy to reach an outer energy level so it has the lowest first ionization potential. Therefore, magnesium will react most readily with HCl.

geosphere and hydrosphere.

this is because the geosphere has to do with geological events, while the hydrosphere controls all water on earth.