Practice question

Given: The number of electrons in the valence shell of an element with configuration 1s² 2s² 2p⁶ 3s² is: Formula: Magnesium (Mg, Z=12) has 3s² in its valence shell (n=3), totaling 2 valence electrons.. Substitution: Substituting given values into formula as per NCERT 2026-27 method. Calculation: Simplifying step by step with proper SI units like m/s², J kg⁻¹ K⁻¹, 10⁻⁵, A m⁻¹ etc. Final Result: The computed value matches expected outcome and confirms correct choice as per latest NCERT 2026-27.