When `I_(2)` dissociates to its atomic from the following reaction occurs :
`I_(2(g))hArr2I_((g)),DeltaH^(@)=+150" kJ mol"^(-1)`
The reaction is favoured at (a)low temperature (B)high temperature (C)no change with temperature (D)high pressure

Options

A. low temperature
B. high temperature
C. no change with temperature
D. high pressure.

Explanation

To determine the conditions under which the dissociation of iodine gas (I₂) into atomic iodine (I) is favored, we can analyze the given reaction and apply the principles of chemical equilibrium and thermodynamics.

### Given Reaction:
\[ I_2(g) \rightleftharpoons 2I(g) \]
\[ \Delta H^\circ = +150 \, \text{kJ mol}^{-1} \]

### Step-by-Step Solution:

1. **Identify the Nature of the Reaction:**
- The reaction is endothermic because the enthalpy change (\(\Delta H\)) is positive. This means that heat is absorbed when the reaction proceeds in the forward direction (from I₂ to 2I).

2. **Applying Le Chatelier's Principle:**
- According to Le Chatelier's principle, if a system at equilibrium is subjected to a change in temperature, pressure, or concentration, the system will adjust to counteract that change and restore a new equilibrium.

3. **Effect of Temperature:**
- For an endothermic reaction, increasing the temperature shifts the equilibrium to the right (toward the products). Therefore, higher temperatures favor the dissociation of I₂ into atomic iodine (2I). Conversely, lowering the temperature would favor the formation of I₂.

4. **Effect of Pressure:**
- In the given reaction, we have 1 mole of I₂ gas producing 2 moles of I gas. Increasing the pressure will shift the equilibrium toward the side with fewer moles of gas. Since the forward reaction produces more moles (2 moles of I) than the reverse reaction (1 mole of I₂), increasing the pressure will favor the formation of I₂, not its dissociation.

5. **Conclusion:**
- Based on the analysis, the reaction is favored at **high temperature** because it is endothermic. Therefore, the correct answer is:
- **(B) high temperature**