Which of the following observations indicates that an atom has neutrons?
a) some uncharged particles are scattered by a beryllium atom when it hits a gold foil.
b) some uncharged particles bounce back from a gold foil when it is bombarded with alpha particles.
c) radiation consisting of uncharged particles is emitted when alpha particles strike beryllium atoms.
d) radiation which attracts electrons is produced when a beryllium atom is bombarded with alpha particles.

Toluene will be the most suitable solvent.

Explanation:

Recrystallization is the process where an impure solid is dissolved in a solvent at a high temperature (to accelerate the process). Then, the mixture is cooled down, so the solid must be formed again, this time without the impurities, which are dissolved in the solvent.

So, a good solvent, must dissolve all the solute in high temperatures, and can't dissolve it in low temperatures. The only one which does that is the toluene.