Answer:
i. La (s) + O2 (g) => LaO2 (s)
ii. La (s) + O2 (g) => La2O (s)
III. La (s) + O2 (g) => La2O3 (s)
Step-by-step explanation:
Hello there!
When you are given such a problem for completing the chemical equations, what you have to understand is that metals are found in groups I, II and III. While Oxygen is a group VI element.
From the above question I have considered that my La(s), solid is either Sodium (Na) - group I, Magnesium - group II and Aluminum - group III.
In a reaction, there is exchange of electrons given by their oxidation numbers (I, II and III - for our metals above)
The chemical equations are thus;
i. Na (s) + O2 (g) => NaO (s)
ii. Mg (s) + O2 (g) => Mg2O (s)
iii. Al (s) + O2 (g) => Al2O3 (s)
Relate this to the problem and it will be;
i. La (s) + O2 (g) => LaO2 (s)
ii. La (s) + O2 (g) => La2O (s)
III. La (s) + O2 (g) => La2O3 (s)
I hope this helps you to understand better. Enjoy your studies