Question

Among the following which three elements are an example of Dobereiner’s triad. Give
reason.
A ( Z=11), B ( Z=20), C ( Z= 3), D ( Z=19), E (Z= 17)

Answer 1

Answer:

who the hell asked u that bro, we aren't in 1850 anymore

Answer 2

Among the following which three elements are an example of Dobereiner’s triad. Give reason.

A (Z=11), B ( Z = 20), C ( Z = 3), D ( Z = 19), E (Z = 17)

solution : according to Dobereiner's triad, “the arithmetic mean value of atomic masses of 1st and 3rd elements of triad would be approximately equal to the atomic mass of the second element in that triad.”

let's use this concept on above data.

A ⇒ Z = 11 (Na ) atomic mass = 23

B⇒Z = 20 (Ca) atomic mass = 40

C ⇒Z = 3 (Li) atomic mass = 7

D⇒ Z = 19 (K) atomic mass = 39

E ⇒ Z = 17 (Cl) atomic mass = 35.5

if we choose, Li, Na and K as 1st , 2nd and 3rd respectively.

arithmetic mean of 1st and 3rd = (7 + 39)/2 = 46/2 = 23

Therefore Li, Na and K is Dobereiner's triad.

so there is only one triad and that is C , A, and D