5. What does it mean if an isotope is "fissile"?

What is the number of moles of chemical units represented by 9.03x10^24? and how do i show work? (dumb it down )

In the particles are arranged in a regular, repeating pattern. a)a crystalline liquid b)a crystalline solid c)all gases d)all solids

Isopropyl alcohol, (ch3)2choh, is a common solvent. determine the percent by mass of hydrogen in isopropyl alcohol. a) 6.71% h b) 13.4% h c) 25.0% h d) 53.3% h