Which of the following is pseudo first order reaction?
I. `CH_(3)COOC_(2)H_(5)+H_(2)O overset(H^(+)) rarr CH_(3)COOH +C_(2)H_(5)OH`
II. `C_(12)H_(22)O_(11)+H_(2)O overset(H^(+)) rarr C_(6) H_(12)O_(6) +C_(6)H_(12)O_(6)`

Options

A. only I
B. only II
C. both I & II
D. none of these

Explanation

To determine which of the given reactions is a pseudo first-order reaction, we need to analyze both reactions in terms of their rate laws and the role of water as a reactant.

### Step 1: Understanding Pseudo First-Order Reactions
A pseudo first-order reaction occurs when one of the reactants is present in a large excess, making its concentration effectively constant during the reaction. This allows the reaction to be treated as a first-order reaction with respect to the other reactant.

### Step 2: Analyzing the First Reaction
The first reaction is:
\[ CH_3COOC_2H_5 + H_2O \overset{H^+}{\rightarrow} CH_3COOH + C_2H_5OH \]

- Here, the reactants are ethyl acetate (CH₃COOC₂H₅) and water (H₂O).
- Water is typically present in large excess in hydrolysis reactions, making its concentration effectively constant.
- Therefore, we can express the rate law as:
\[ \text{Rate} = k' [CH_3COOC_2H_5] \]
where \( k' = k[H_2O] \) (with \( k \) being the rate constant for the reaction).
- Since water is in excess, this reaction behaves as a pseudo first-order reaction.

### Step 3: Analyzing the Second Reaction
The second reaction is:
\[ C_{12}H_{22}O_{11} + H_2O \overset{H^+}{\rightarrow} C_6H_{12}O_6 + C_6H_{12}O_6 \]

- The reactants are sucrose (C₁₂H₂₂O₁₁) and water (H₂O).
- Similar to the first reaction, water is also present in large excess in this hydrolysis reaction.
- Thus, we can express the rate law as:
\[ \text{Rate} = k' [C_{12}H_{22}O_{11}] \]
where \( k' = k[H_2O] \).
- Again, since water is in excess, this reaction also behaves as a pseudo first-order reaction.

### Conclusion
Both reactions are pseudo first-order reactions because water is present in large excess in both cases.

### Final Answer
Both reactions (I and II) are pseudo first-order reactions.