Which of the following is not a clue that chemical change is taking place

3 hours because it is a decent distance.

the answer would be a

atomic mass = 39

number of neutrons = 20

number of protons= 19

electronic configuration = 1s2 2s2 2p6 3s2 3p6 4s1

the number of electron in first shell = 2

number of electrons in n=3 shell = 8

i think its 100

i hope this !