The questions given below consist of Assertion (A) and Reason (R ) . Use the following key to select the correct answer.
Assertion : In Zeise's salt, co-ordianation number of Pt is five.
Reason : Ethene is a bidentate lignad .

Options

A. If both assertion and reason are true and reason is the correct explanation of assertion.
B. If both assertion and reason are true but reason is not the correct explanation of assertion.
C. If assertion is true but reason is false.
D. If both asertion and reason are false.

Explanation

To solve the question, we need to analyze both the Assertion (A) and the Reason (R) provided.

### Step 1: Analyze the Assertion
- **Assertion (A)**: "In Zeise's salt, the coordination number of Pt is five."
- Zeise's salt is a coordination compound with the formula [PtCl3(C2H4)]^−. In this compound, platinum (Pt) is coordinated to three chloride ions (Cl^−) and one ethylene molecule (C2H4).
- The coordination number is defined as the number of ligand atoms that are bonded to the central metal atom. In this case, Pt is bonded to four ligands (three Cl^− and one C2H4).
- Therefore, the coordination number of Pt in Zeise's salt is **4**, not 5. This means the assertion is **false**.

### Step 2: Analyze the Reason
- **Reason (R)**: "Ethene is a bidentate ligand."
- A bidentate ligand is one that can form two bonds with the central metal atom. Ethene (C2H4) has a double bond between the two carbon atoms, and it does not have two donor atoms to bind to the metal center.
- Ethene acts as a **monodentate ligand**, meaning it can only form one bond with the metal. Thus, the reason is also **false**.

### Conclusion
- Since both the assertion and the reason are false, the correct answer is that both the assertion and reason are false.

### Final Answer
- Both assertion and reason are false.