Which of the following statement are correct ?

Options

A. The electronic configuration of `Cr` is `[Ar]3d^(5), 4s^(1)` (atomic number of Cs = 24)
B. The magnitic quantum number may have a negative value
C. In silver atom `23` electron have spin of one type and `24` of the opposite type .(Atomic number of `Ag = 47)`
D. The oxidation state of nitrogen in `NH_(3)` is `-3`

Answer

To determine which of the statements are correct, we will evaluate each statement one by one.

### Step 1: Evaluate the first statement
**Statement:** The electronic configuration of chromium is argon 3d5 and 4s1.

**Analysis:**
- The atomic number of chromium (Cr) is 24.
- The expected electronic configuration based on the Aufbau principle would be:
- 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁴ (which is argon 3d4 4s2).
- However, chromium is an exception to this rule. To achieve a more stable configuration, one electron from the 4s subshell is promoted to the 3d subshell, resulting in the configuration:
- 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁵ 4s¹ (which is argon 3d5 4s1).
- **Conclusion:** This statement is correct.

### Step 2: Evaluate the second statement
**Statement:** The magnetic quantum number may have negative values.

**Analysis:**
- The magnetic quantum number (m) can take values from -l to +l, where l is the azimuthal quantum number.
- For example, if l = 2 (which corresponds to the d subshell), m can take values: -2, -1, 0, +1, +2.
- **Conclusion:** This statement is correct.

### Step 3: Evaluate the third statement
**Statement:** In a silver atom (Ag), 23 electrons have the same spin and 24 have opposite spin.

**Analysis:**
- The atomic number of silver (Ag) is 47.
- In the ground state, silver has a configuration of:
- [Kr] 4d¹⁰ 5s¹.
- This means that there are 10 electrons in the 4d subshell (which are paired) and 1 unpaired electron in the 5s subshell.
- The statement seems to imply that 23 electrons are paired and 24 have opposite spins, which is misleading.
- **Conclusion:** This statement is incorrect.

### Step 4: Evaluate the fourth statement
**Statement:** The oxidation state of nitrogen in NH3 is -3.

**Analysis:**
- In ammonia (NH3), let the oxidation state of nitrogen be X.
- The oxidation state of hydrogen is +1.
- The equation for the total oxidation state in a neutral compound is:
- X + 3(+1) = 0
- X + 3 = 0
- X = -3.
- **Conclusion:** This statement is correct.

### Final Conclusion:
The correct statements are:
1. The electronic configuration of chromium is argon 3d5 and 4s1. (Correct)
2. The magnetic quantum number may have negative values. (Correct)
3. In silver atom, 23 electrons have the same spin and 24 have opposite spin. (Incorrect)
4. The oxidation state of nitrogen in NH3 is -3. (Correct)

### Summary of Correct Statements:
- Statements 1, 2, and 4 are correct. Statement 3 is incorrect.