Question

Please solve this question of chemistry chapter 4

Answer 1

Mass number (protons+neutrons)
X- 11+13=24
Y- 12+12=24

Atomic mass (no. of protons in the nucleus)
X-11 (sodium)
Y-12 (magnesium)

Relation
Both have same atomic mass
Both are metals as they have 1 and 2 valence electrons respectively(2,8,1) and (2,8,2)