Is the number of atoms in a substance dependent on the type of substance present?

Calculate the change in entropy if br2(l) is converted into gaseous br atoms. s° for br2(l) = 152.2 j/(mol•k) s° for br2(g) = 245.5 j/(mol•k) s° for br(g) = 175.0 j/(mol•k)

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

What happens to isotopes that are unstable?