Answer:
a) ZnCl₂; Zn + 2HCl ⟶ ZnCl₂ + H₂
b) MgO; 2Mg + O₂ ⟶ 2MgO
c) Al₂O₃; 4Al + 3O₂ ⟶ 2Al₂O₃
Explanation:
a) Zn + HCl
(i) Identify the missing compound
Zn + HCl ⟶ a +H₂
We have Zn and Cl on the left but not on the right.
a = ZnCl₂
(ii) Write the balanced equation
Zn + 2HCl ⟶ ZnCl₂ + H₂
b) 2Mg
(i) Identify the missing element
2Mg + b ⟶ 2MgO
We have O on the right but not on the left.
b = O₂
(ii) Write the balanced equation
2Mg + O₂ ⟶ 2MgO
c) 4Al + 3O₂
(i) Identify the missing compound
4Al + 3O₂ ⟶ c
We have Al and O on the left but not on the right.
The missing substance must be a compound of Al and O₂.
c = Al₂O₃
(ii) Write the balanced equation
4Al + 3O₂ ⟶ 2Al₂O₃