Which substances have atoms of the same element but different molecular structures?
a. he(g) and ne(g)
b. k(s) and na(s)
c. o2(g) and o3(g)
d. p4(s) and s8(s)

Match term definition ellipse a) diagonal cross section of a cylinder circle b) diagonal cross section through the widest part of a sphere sphere c) cross section parallel to the base of a cone great circle d) shape created when a semi-circle is rotated around the y-axis triangle e) perpendicular cross section of a cone

What is the percent by mass of oxygen in fe2o3

If anyone would be able to me out with these three questions it would be these are from the chem 2202 course.