The emission spectrum of an element:

a. may be identical to the emission spectrum of another element.

b. is identical to its absorption spectrum.

c. may be identical to the absorption spectrum of another element.

d. is different from any other element's absorption spectrum.

because u need two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei to form isotopes.

so since they all have the same shape? i mean maybe because m& m and reeses are both chocolates

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