What is the metal ion in the porphyrin of heme?
A) iron
B) calcium
C) molybdenum
D) magnesium
E) chlorophyll
Question 2
The modern periodic law states that the properties of the elements repeat when the periodic table is arranged according to which of the following?
A) increasing atomic number
B) increasing mass number
C) increasing atomic mass
D) increasing isotopic mass
E) none of the above
