1- Which of the following elements tends to form the oxide MO3 (give reason)

(₂₅Mn , ₂₄Cr , ₂₃V) 

Ans :    Cr                   ₂₄Cr : Ar₁₈ 4S², 3d⁴   ............. ₂₄Cr⁶ : Ar₁₈ 4S⁰,3d⁰

2-  Which of the following elements form with chlorine the compound MCl4 (give reason)

(₂₂Ti , ₂₆Fe , ₂₉Cu).

Ans : Ti             ₂₂Ti :Ar₁₈ 4S² , 3d² ...............₂₄Ti⁴ : Ar₁₈ 4S⁰,3d⁰