Statement-1 : The groundstate configuration of Cr is [Ar] `3d^(5) 4s^(1)`
Statement-2 : The energy of atom is lesser in `3d^(5)4s^(1)` configuration compared to `3d^(4)4s^(2)` configuration.

Options

A. Statement-1 is true, statement-2 is true and statement-2 is correct explanation for statement-1.
B. Staterment-1 is true, statement-2 is true and statement-2 is NOT the correct explanation for statement-1.
C. Statement-1 is true, statement-2 is false.
D. Statement-1 is false, statement-2 is true.

Answer

To solve the question, we need to analyze both statements regarding the ground state electron configuration of chromium (Cr) and the energy levels associated with different configurations.

### Step 1: Analyze Statement-1
The ground state configuration of chromium (Cr) is given as [Ar] `3d^(5) 4s^(1)`.

- Chromium has an atomic number of 24, which means it has 24 electrons.
- The expected electron configuration based on the Aufbau principle would be [Ar] `3d^(4) 4s^(2)`. However, chromium is an exception to this rule.
- The actual configuration is [Ar] `3d^(5) 4s^(1)` because having a half-filled d-subshell (3d) provides extra stability due to symmetry and exchange energy.

### Step 2: Analyze Statement-2
The second statement claims that the energy of the atom is lesser in the `3d^(5) 4s^(1)` configuration compared to the `3d^(4) 4s^(2)` configuration.

- A half-filled d-subshell (3d) is more stable than a partially filled one (3d with 4 electrons).
- The stability arises from the symmetrical distribution of electrons and the maximization of exchange energy, which lowers the overall energy of the atom.
- Therefore, the configuration `3d^(5) 4s^(1)` is indeed lower in energy and more stable than `3d^(4) 4s^(2)`.

### Conclusion
Both statements are correct:
- Statement-1 is correct as it accurately describes the ground state configuration of chromium.
- Statement-2 is also correct as it explains the stability and lower energy associated with the `3d^(5) 4s^(1)` configuration compared to `3d^(4) 4s^(2)`.

Thus, the answer is that both statements are true and Statement-1 provides a correct explanation for Statement-2.

### Final Answer
Both statements are true, and Statement-1 is the correct explanation for Statement-2.

---