The number of electrons in an element x is 15 and the number of neutrons is 16. Which of the following is the correct representation of the element? (a) 31 15 x (b) 31 16 x (c) 16 15 x (d) 15 16 x.

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

you need to stop taking that class

alchemy hadn't scientific methods of study, appeal to mysticism and fantasy, the knowledge of chemistry and physics were modest at that time.

alchemy was - but as new rules were discovered it either changed into chemistry or it became "unscientific".