Question

Can someone please use a periodic table and figure this out? I’m stuck.

Answer 1

I can help with the first one and third for you.

Symbol |  atomic # | Mass of # | # of Protons | # of electrons | # of neutrons

Na        |   11      |   23 (when rounded)  | 11  |                     11       | 12

Sr        |  38     |   88 (when rounded)   | 38 |                    38     | 50

(sorry if this didn't help)