Question

20 element and atomic number

Answer 1

Explanation:

is a right and correct answer

Answer 2

Answer:

hydrogen =1

helium =2

lithium =3

beryllium =4

boron = 5

carbon = 6

nitrogen = 7

oxygen =8

fluorine =9

neon =10

sodium =11

magnesium=12

aluminium=13

silicon =14

phosphorous=15

sulfur = 16

chlorine =17

argon =18

potassium=19

calcium =20