A s-block element (M) reacts with oxygen to form an oxide of the formula MO 2 . The oxide is pale yellow in colour and paramagnetic. The element ( M ) is:

Step-by-step solution

(A) 2 Mg + O 2 → 2 MgO (Diamagnetic) (B) 2 Na + O 2 → Na 2 O (Diamagnetic) 2 Na + O 2 ( excess ) → Na 2 O 2  (Diamagnetic) (C) 2 Ca + O 2 → 2 CaO (Diamagnetic) Ca + O 2 → CaO 2 (Diamagnetic) (D) K + O 2  (excess)  → KO 2  (Paramagnetic)