Triad among the following is

Options

A. H, F, CI
B. F, CI, Br
C. Be, Mg, Ca
D. Ca, Sr, Ba

Answer

C

Explanation

Triad are the elements having the atomic mass of the middle element is roughly the average of the atomic masses of the other elements .
(a) `" "` H,F,CI
Atomic masses = 1,19.0 , 35.5
(b)` " "` F,CI,Br
Atomic masses = 19.0 ,35.5 , 79.9
= 49.45
(c) `" "` Be,Mg,Ca
Atomic masses = 9.0 ,24.3,40.1
= 24.55
(d) `" "` Ca,Sr,Ba
Atomic masses = 40.1 , 87.6,137.3
= 88.7
Among given option , Be Mg, Ca will be make triad
`(9.0 + 40.1)/(2) = 24 .55 = 24.3`