Determine the number of protons and neutrons in a carbon-14 isotope and write its symbol in the form azx.

n has four pairs of electrons in the valence shell, electrons repel one another ,n has 7 protons in its nucleus, and since n has 7 protons, it must fill the second shell, giving it 4 pairs of electrons. the electrons form 3 bonds and 1 lone pair of electrons. each pair of electrons repels the other pairs, so they are equally far apart.

so all of the above

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