Question

In Sr (Z=38), the number of electrons with \(l=0\) is x, number of electrons with \(l=2\) is y. \((x-y)\) is equal to (\(l\) = Azimuthal quantum number)

• A. 0
• B. 8
• C. -2
• D. 2

Hint:

When your logical calculation from the given data leads to an answer that is not in the options, or contradicts the provided answer key, look for potential typos in the question. Common typos are in atomic numbers (Z), quantum numbers, or chemical formulas.

Answer 1

The Correct Option is C

Step 1: Electronic Configuration of Strontium (Z=38): Using Aufbau principle: \( 1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^6 5s^2 \). Rearranging by shell: \( 1s^2, 2s^2, 2p^6, 3s^2, 3p^6, 3d^{10}, 4s^2, 4p^6, 5s^2 \).
Step 2: Count electrons with \( l=0 \) (s-orbitals): Orbitals: \( 1s, 2s, 3s, 4s, 5s \). Number of electrons \( x = 2 + 2 + 2 + 2 + 2 = 10 \).
Step 3: Count electrons with \( l=2 \) (d-orbitals): Orbitals: \( 3d \). (4d is empty as Sr is Group 2 Period 5). Number of electrons \( y = 10 \) (from \( 3d^{10} \)).
Step 4: Calculate \( x-y \): \( x - y = 10 - 10 = 0 \).