I came up with a required balloon volume of 476 before adding the extra 1 mL.
Explanation:
Lithium, sodium and potassium are all group 1A elements and when we move down a group then there occurs an increase in atomic size of the elements. As lithium is the smallest and potassium being the largest so, when each of them will lose an electron and obtain a positive charge then size of lithium will further decrease.
Therefore, ions are ranked according to their increase in size as follows.
When an atom tends to gain electrons then it acquires a negative charge. This means that size of the atom increases.
So, more is the negative charge present on an atom more will be its atomic size. Therefore, correct order of increasing size for
is as follows.

Similarly, order of increasing size of
is as follows.

Because Arsenic is in group 15 it will receive 5 valence electrons Start out by adding one dot around the symbol for Arsenic. You'll end up with 4 around it and <span>all you have to do is add another one.</span>