An element is pla

(a) The element placed in 2nd Group and 3rd Period of the Periodic Table is Magnesium (Mg).

(b) Electronic configuration: 1s², 2s² 2p⁶ 3s²

K, L, M

2, 8, 2

(c) When the magnesium metal burns in oxygen, it produces magnesium oxide.

2Mg(s) + O₂(g) → 2MgO(s)

When magnesium oxide is heated with water, magnesium hydroxide is formed.

(d) MgO(s) + H₂O(l) → Mg(OH)₂(aq)

Electron dot structure:

Magnesium loses two electrons and oxygen gains two electrons to complete the octet structure.