What is the average atomic mass of hafnium given the following abundance information on the isotopes? [Hf-176 (mass 176 amu) has an abundance of 5%]
[Hf-177 (mass 177 amu) has an abundance of 19%]
[Hf-178 (mass 178 amu) has an abundance of 27%]
[Hf-179 (mass 179 amu) has an abundance of 14%]
[Hf-180 (mass 180 amu) has an abundance of 35%]

Both 1,2−dihydronaphthalene and 1,4−dihydronaphthalene may be selectively hydrogenated to 1,2,3,4−tetrahydronaphthalene. one of these isomers has a heat of hydrogenation of 101 kj/mol (24.1 kcal/mol), and the heat of hydrogenation of the other is 113 kj/mol (27.1 kcal/mol). match the heat of hydrogenation with the appropriate dihydronaphthalene.

What happened in 2012 and how does it illustrate the importance of understanding the sun and how it works?

Place the elements below in order of decreasing ionization energy. aluminum(al) chlorine(cl) magnesium (mg) sulfur(s)