What is ionization energy?
a) the minimum energy required to remove one electron from an atom.
b) the maximum energy required to remove one electron from an atom.
c) the maximum energy required to move one electron to the valence shell.
d) the minimum energy required to move one electron to the valence shell.

c. heat could easily travel through the molecules in the air and escape/enter the flask. removing the air slows down the heat transfer.  

because u need two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei to form isotopes.

so since they all have the same shape? i mean maybe because m& m and reeses are both chocolates