What element has the same electron configuration of 1s2 2s2 2p6 3s2 3p6 ?

Ar

Explanation:

1s2|2s2 2p6|3s2 3p6 means 2+2+6+2+6=18 electrones. Also it means the number in the table.

According to the №18 the requested element is Argon.

so here we go

atomic mass

239 + 1 = y + 134 + 3 combine like terms

240 = y + 137             subtract 137 from both terms

240 - 137 = y

103 = y

atomic number

94 = z +54 + 0

94 = z + 54               subtract 54 from both sides.

40 = z

answer

the answer is c

tell me if wrong