Fill in the blanks with appropriate word/s from the brackets :

Covalent compounds are formed by sharing electron pairs between non-metallic atoms. Non-metallic atoms having …………… , …………… , …………… valence electrons (4, 5, 6, 7) share one, two or three pairs of electrons respectively.

Explain the terms 'oxidation' and reduction' with reference to an atom or ion.

State which of the following are oxidation reactions and which are reduction reactions.

(a) (i) Cu ⟶ Cu²⁺ + 2e^-

(ii) Cu²⁺ + 2e^- ⟶ Cu

(iii) Sn⁴⁺ + 2e^- ⟶ Sn²⁺

(iv) 2Cl^- ⟶ Cl₂ + 2e^-

(v) Fe²⁺ ⟶ Fe³⁺ + 1e^-

(vi) X + 2e^- ⟶ X^2-

(vii) Y - 1e^- ⟶ Y¹⁺

(viii) Z³⁺ + 1e^- ⟶ Z²⁺

(b) (i) Zn ⟶ Zn²⁺

(ii) S ⟶ S^2-

(iii) Sn²⁺ ⟶ Sn

(iv) Fe²⁺ ⟶ Fe³⁺

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NaCl an electrovalent compound is formed as a result of transfer of …………… (one, two, three) valence electrons from metallic sodium to non-metallic chlorine atom. CaO is similarly formed as a result of transfer of …………… (one, two, three) valence electron/s from metallic calcium to non-metallic oxygen and magnesium chloride by transfer of …………… (one, two, three) valence electron/s from …………… (one, two) magnesium atom/s to …………… (one, two) chlorine atom/s.