What do the following atoms have in common? Fe2+, Fe3+, Fe-54, Fe-59
A. radioactivity
B. atomic mass
C. atomic number
O D. number of neutrons
E. number of electrons

2pos suppose an object in free fall is dropped from a building. its starting velocity is 0 m/s. ignoring the effects of air resistance, what is the speed (in m/s) of the object after falling 3 seconds? give your answer as a positive decimal without units. answer here

Which element has the lowest electronegativity? calcium(ca) gallium(ga) selenium(se) bromine(br)

12. calculate the hydroxide ion concentration of a solution with ph = 3.25. show all calculations leading to an answer