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. R exhibits maximum covalency among all elements given
B. Q does not exhibit variable covalency
C. R exhibits minimum covalency among all elements given
D. R and S combine each other and form `SR_(5)` type of compound

Explanation

To solve the question, we need to analyze the provided statements about the elements and determine which one is incorrect based on their properties and covalency.

### Step-by-Step Solution:

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

2. **Evaluate Each Statement:**
- **Statement A:** "R exhibits minimum covalency among all elements given."
- Chlorine (R) has 7 valence electrons and can form a covalent bond by accepting or sharing electrons. Its minimum covalency is 1 (when it forms Cl-).
- **Statement B:** "Q does not exhibit variable covalency."
- Oxygen (Q) typically has a covalency of 2 and does not exhibit variable covalency due to its high electronegativity.
- **Statement C:** "R exhibits minimum covalency among all elements given."
- This is the same as Statement A, which we already evaluated as correct.
- **Statement D:** "R and S combine with each other to form SR5 type of compound."
- Chlorine (R) and Aluminum (S) do not form AlCl5; instead, they form AlCl3. Aluminum does not expand its octet, so this statement is incorrect.

3. **Conclusion:**
- The incorrect statement is **D**: "R and S combine with each other to form SR5 type of compound."

### Final Answer:
The incorrect statement is **D**.