Read the following statements and mark the incorrect statement.

Options

A. No two electrons in an atom can have all the four quantum number same.
B. All the orbitals in a subshell are first occupied singly with parallel spins.
C. The outer electronic configuration of chromium atom is `3d^(4)4s^(2)`.
D. Lyman series of hydrogen spectrum lies in ultraviolet region.

Explanation

To solve the question, we need to analyze each statement provided and determine which one is incorrect. Here’s a step-by-step breakdown:

### Step 1: Analyze Statement A
**Statement A:** No two electrons in an atom can have all the four quantum numbers the same.

- **Explanation:** This statement is based on the Pauli Exclusion Principle, which states that no two electrons in an atom can have the same set of four quantum numbers. This means that while the principal (n), azimuthal (l), and magnetic (m) quantum numbers can be the same for two electrons, the spin quantum number (s) must be different (one must be +1/2 and the other -1/2).
- **Conclusion:** This statement is **correct**.

### Step 2: Analyze Statement B
**Statement B:** All the orbitals in a subshell are first occupied singly with parallel spins.

- **Explanation:** This statement refers to Hund's Rule, which states that electrons will fill degenerate orbitals (orbitals of the same energy) singly and with parallel spins before pairing up. This minimizes electron-electron repulsion and maximizes stability.
- **Conclusion:** This statement is **correct**.

### Step 3: Analyze Statement C
**Statement C:** The outer electronic configuration of chromium atom is 3d⁴ 4s².

- **Explanation:** Chromium (Cr) has an atomic number of 24. The expected electron configuration would be 3d⁴ 4s². However, due to stability reasons (to achieve a half-filled d subshell), one electron from the 4s subshell is promoted to the 3d subshell. Thus, the correct configuration is 3d⁵ 4s¹.
- **Conclusion:** This statement is **incorrect**.

### Step 4: Analyze Statement D
**Statement D:** Lyman series of hydrogen spectrum lies in the ultraviolet region.

- **Explanation:** The Lyman series corresponds to transitions of electrons from higher energy levels to the first energy level (n=1) in hydrogen. These transitions emit ultraviolet light.
- **Conclusion:** This statement is **correct**.

### Final Conclusion
After analyzing all statements, the incorrect statement is **Statement C**: "The outer electronic configuration of chromium atom is 3d⁴ 4s²."

### Answer
The incorrect statement is **C**.

---