The number f-electrons in +3 oxidation state of gadolinium (Z=64) is x and in +2 oxidation state of Ytterbium ( Z =70) is y . The sum of x and y is

Step-by-step solution

The outer electronic configuration for Gd and Yb are:- aligned & Gd =4 f^7 5 ~d ^1 6 ~s ^2 & Yb =4 f¹⁴ 6 ~s ^2 aligned Thus, Gd ³⁺=4 f^7 and yb ²⁺=4 f¹⁴ Thus, x=7 and y=14 x+y=7+14=21