Give one example of a chemical reaction.

(i) Na + 0₂ Na₂0

(ii) H₂0₂H₂0 + 0₂

(iii) Mg(OH)₂ +HCl MgCl₂+ H₂0

(iv) Fe +0₂Fe₂0₃

(v) Al(OH)₃Al₂0₃ + H₂0

(vi) NH₃ + CuO Cu +N₂+ H₂0

(vii) Al₂(S0₄)₃ + NaOH Al(OH)₃ + Na₂S0₄

(viii) HN0₃ +Ca(OH)₂Ca(NO₃)₂ + H₂O

(ix) NaOH+H₂S0₄Na₂SO₄ +H₂O

(x) BaCl₂+H₂S0₄ BaSO₄+ HCl

(a) Chemical equations are balanced to satisfy the law of ........

(b) A solution made in water is known as an ............ solution and indicated by the symbol ..............