Assertion: Formaldehyde is a planar molecule.
Reason: It contains `sp^(2)` hybridised carbon atom.

Options

A. Assertion and reason both are correct and reason is correct explanation of assertion.
B. Assertion and reason both are wrong statement.
C. Assertion is correct statement but reason is wrong statement.
D. Assertion is wrong statement but reason is correct statement.

Explanation

To solve the question, we need to analyze both the assertion and the reason provided.

### Step 1: Understanding the Assertion
The assertion states that "Formaldehyde is a planar molecule." To determine if this is true, we need to consider the molecular geometry of formaldehyde.

### Step 2: Analyzing the Structure of Formaldehyde
Formaldehyde (CH₂O) consists of one carbon atom, two hydrogen atoms, and one oxygen atom. The carbon atom is bonded to two hydrogen atoms and one oxygen atom through a double bond.

### Step 3: Hybridization of Carbon in Formaldehyde
The carbon atom in formaldehyde undergoes hybridization. In this case, it is sp² hybridized. This means that one s orbital and two p orbitals from the carbon atom combine to form three equivalent sp² hybrid orbitals. The remaining p orbital is used to form a π bond with the oxygen atom.

### Step 4: Geometry of the Molecule
The three sp² hybrid orbitals arrange themselves in a trigonal planar geometry, which is characterized by bond angles of approximately 120 degrees. This arrangement leads to a planar structure for the molecule.

### Step 5: Conclusion on the Assertion
Since the geometry of formaldehyde is trigonal planar, we conclude that the assertion "Formaldehyde is a planar molecule" is true.

### Step 6: Understanding the Reason
The reason states that "It contains sp² hybridized carbon atom." Since we have established that the carbon atom in formaldehyde is indeed sp² hybridized, this reason is also true.

### Step 7: Relationship Between Assertion and Reason
The reason correctly explains why the assertion is true. The sp² hybridization of the carbon atom leads to the trigonal planar geometry of formaldehyde, confirming that it is a planar molecule.

### Final Conclusion
Both the assertion and the reason are true, and the reason provides a correct explanation for the assertion.

### Final Answer
Assertion: True
Reason: True
Both are correct, and the reason is the correct explanation of the assertion.

---