The standard enthalpies of formation of three substances A, B and C are 201.6, -52.6 and -106.4 kJ respectively.Arrange them in order of decreasing stability with respect to decomposition.

Explanation

To determine the order of stability of substances A, B, and C with respect to decomposition, we need to analyze their standard enthalpies of formation. The stability of a substance is inversely related to its enthalpy of formation: the more negative the enthalpy, the more stable the substance is against decomposition.

### Step-by-Step Solution:

1. **Identify the Standard Enthalpies of Formation**:
- For substance A: \( \Delta H_f^\circ = +201.6 \, \text{kJ} \)
- For substance B: \( \Delta H_f^\circ = -52.6 \, \text{kJ} \)
- For substance C: \( \Delta H_f^\circ = -106.4 \, \text{kJ} \)
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