Consider the following elements with their period number and valence electrons.
`{:("Elements","Period number","Total valence"e^(-)),(P,2,4),(Q,2,6),(R,3,7),(S,3,3),(T,3,6),(U,3,4):}`
According to the given informations, answer the following questions :
Choose incorrect statement :

Options

A. `SR_(3)` is a hypovalent compound
B. `UR_(4)` can act as a Lewis acid
C. `PQ_(2)` can not acts as Lewis acid
D. `UR_(4) gt SR_(3)` : Lewis acidic character

Explanation

To solve the question, we need to analyze the statements related to the elements P, Q, R, S, T, and U based on their period numbers and valence electrons. We will identify the incorrect statement among the options provided.

### Step-by-Step Solution:

1. **Identify the Elements and Their Properties**:
- P: Period 2, 4 valence electrons (Carbon, C)
- Q: Period 2, 6 valence electrons (Oxygen, O)
- R: Period 3, 7 valence electrons (Chlorine, Cl)
- S: Period 3, 3 valence electrons (Aluminum, Al)
- T: Period 3, 6 valence electrons (Sulfur, S)
- U: Period 3, 4 valence electrons (Silicon, Si)

2. **Analyze Each Element's Behavior**:
- **P (C)**: Carbon can form four bonds and is not a Lewis acid.
- **Q (O)**: Oxygen can accept electrons and can act as a Lewis acid in certain reactions.
- **R (Cl)**: Chlorine can accept electrons and can act as a Lewis acid.
- **S (Al)**: Aluminum is known to be a Lewis acid as it can accept electron pairs.
- **T (S)**: Sulfur can also act as a Lewis acid.
- **U (Si)**: Silicon can act as a Lewis acid because it can accept electron pairs.

3. **Determine the Incorrect Statement**:
- The question states to choose the incorrect statement regarding these elements. Based on the analysis:
- If any statement claims that Carbon (C) or Silicon (Si) cannot act as a Lewis acid, that would be incorrect.
- If any statement claims that Aluminum (Al) is not a Lewis acid, that would also be incorrect.

4. **Conclusion**:
- After analyzing the potential statements, we find that the statement claiming that Carbon (C) or Silicon (Si) cannot act as a Lewis acid is incorrect. Therefore, we conclude that the incorrect statement is related to the behavior of Carbon or Silicon.

### Final Answer:
The incorrect statement is that Carbon (C) or Silicon (Si) cannot act as a Lewis acid.