Which of the following triads does not follow
Dobereiner's law of triads?

Options

A. (a) Li, Na, K
B. (b) Ca, Sr, Ba
C. (c) Be, Mg, Ca
D. (d) Cu, Ag, Au

Explanation

To solve the question of which triad does not follow Dobereiner's law of triads, we will analyze each option provided.

### Step-by-Step Solution:

1. **Understanding Dobereiner's Law of Triads**:
- Dobereiner's law states that when three elements (A, B, C) are arranged in a triad, the atomic mass of the middle element (B) should be approximately equal to the average of the atomic masses of the other two elements (A and C).
- Mathematically, this can be expressed as:
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