Answer:
a. X is Na, Y is Mg, Z is Al
b. 2Na + 2H2O = 2NaOH + H2
c. 2Al + 3Cl2 = 2AlCl3
Step-by-step explanation:
The third period contains eight elements: sodium, magnesium, aluminium, silicon, phosphorus, sulfur, chlorine and argon.
a. X is Na, Y is Mg, Z is Al because X, Y, Z are all metals
b. 2Na + 2H2O = 2NaOH + H2
c. 2Al + 3Cl2 = 2AlCl3