17.Unbalanced and incomplete chemical equations are given. Fill up the gaps by selecting from the formulae of the molecules given in brackets. Also balance the given equations. a) Zn + 2HCl → --a-- + H 2 b) 2Mg + --b-- → 2MgO c) 4Al +3O 2 → c

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

the earth would become to overheated and everything alive on it will eventually die from overheating. plants will eventually die as well, water will evaporate, and it will be nothing but a hot planet without anything living on it.