(a) what is the relationship between two elements x and y whose atomic numbers are 18 and 20 repectively but their mass umbers remain the same as 40 ?
(b) are their chemical properties same or different? Explain and support your answer.
(c ) Which has more numbr of electrons Na or `Na^(+)`? why?

Explanation

(a) The elements x and Y are related to each other as isobars
(b) Since the atomic numbers of the elements are different , their chemical properties also different
(c ) The electronic configureations of Na and `Na^(+)` ion are given as follows :
Na(Z=11),K(2),L(8),M(1)
`Na^(+)`(Z=11),/K(2),L(8),M(-)
`Na^(+)` ion is formed when Na atom loses one electron .Therefore Na atom has more electrons (11) than `Na^(+)`ion (10).