Considers dobereinter traid with elements X , Y and Z The sum of atomic weights of extreme elements X and Z is 46 and the different of atomic weights Z and Y is two times the atomic number of oxygen .Identify X Y and Z.

Explanation

Given X+Z=`46rarr(1)`
`Z-Y=16 rarr(2)`
`As (X+Y)/(2)=Y` (Dobereiner's law of triads)
`therefore Y=(46)/(22)=23rarr(3)`
From equation (2) and (3) Z-23 =16 `rarr` Z=39
From equation (1)X+Z=46 `rarr`X+39=49`rarr`X=7
So X,Y and Z are Li Na and K respectively