The equlibrium `2SO_(2(g))+O_(2(g))hArr2SO_(3(g))` shift forward, if

Options

A. A catalyst is used
B. An adsorbent is used to remove `SO_(3)` as soon as it is formed
C. Low pressure
D. Small amounts of reactants are used

Answer

To determine the conditions under which the equilibrium reaction \(2SO_{2(g)} + O_{2(g)} \rightleftharpoons 2SO_{3(g)}\) shifts forward, we can analyze the factors that affect chemical equilibrium according to Le Chatelier's principle.

### Step-by-Step Solution:

1. **Understanding the Reaction**: The reaction involves the conversion of sulfur dioxide (\(SO_2\)) and oxygen (\(O_2\)) into sulfur trioxide (\(SO_3\)). The forward reaction is favored under certain conditions.

2. **Effect of Concentration**: Increasing the concentration of the reactants (\(SO_2\) or \(O_2\)) will shift the equilibrium to the right, favoring the formation of \(SO_3\). Conversely, removing \(SO_3\) as it forms will also shift the equilibrium to the right.

3. **Effect of Pressure**: Since there are 3 moles of gas on the left side (2 moles of \(SO_2\) and 1 mole of \(O_2\)) and 2 moles of gas on the right side (2 moles of \(SO_3\)), increasing the pressure will shift the equilibrium towards the side with fewer moles of gas, which is the right side in this case.

4. **Effect of Temperature**: The reaction is exothermic (releases heat). According to Le Chatelier's principle, increasing the temperature will shift the equilibrium to the left (towards the reactants), while decreasing the temperature will shift it to the right (towards the products).

5. **Use of Catalysts**: Adding a catalyst does not shift the position of equilibrium; it only speeds up the rate at which equilibrium is reached. Therefore, while a catalyst can help achieve the forward reaction more quickly, it does not change the equilibrium position.

6. **Conclusion**: The equilibrium shifts forward (to the right) if:
- The concentration of \(SO_2\) or \(O_2\) is increased.
- \(SO_3\) is removed as soon as it is formed.
- The pressure is increased.
- The temperature is decreased.

### Final Answer:
The equilibrium \(2SO_{2(g)} + O_{2(g)} \rightleftharpoons 2SO_{3(g)}\) shifts forward if the concentration of reactants is increased, \(SO_3\) is removed, pressure is increased, or temperature is decreased.