Question

The set of elements (C, N, O) cannot be grouped as Dobereiner's triads because ( A ) they are all non metals. (B ) they have different physical and chemical properties. ( C ) their atomic masses are not in the increasing order. (D ) The atomic mass of N is not an average of atomic masses of C and

Answer 1

Answer:

Te set of [C, N, O] can be grouped as Dobereiner's Triads because

(D) The atomic mass of N is the average of atomic masses of C and O

Explanation:

Dobereiner's Triads

$\blacksquare$ Johann Wolfgang Dobereiner attempted to sort early chemical elements into logical sequences using their atomic masses

$\blacksquare$ He considered a set of three elements where, the average atomic mass of two elements would be equal to the third element

$\blacksquare$ For example, if A, B, C are three elements then,

Mass of B = Average mass of A and C or

$B = \dfrac{A+C}{2}$

$\blacksquare$ His concept were correct only some set of elements like :

1. [Li, Na, K]
2. [Ca, Sr, Ba]
3. [Cl, Br, I]

$\blacksquare$ In the case of [C, N, O] :

Mass of C = 12

Mass of N = 14

Mass of O = 16

Since,

14 = (12 + 16)/2

14 = 28/2

14 = 14