A question about teaching which requests Two elements that make XY2 and XY4 molecules was recently closed as "Needs more focus":
Needs more focus - if your question has many valid answers (but no way to determine which - if any - are correct), then it probably needs to be more focused to be successful in our format.
Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. Avoid asking multiple distinct questions at once. See the How to Ask page for help clarifying this question.
This can often be fixed by breaking the question into multiple questions or focusing on a specific part of the problem.
However, this question is highly focused. The question has so far attracted three upvoted answers. The question asks a single question, which is even presented as bold text in the question body to make it clear.
The question asks a single, answerable query relating to chemical phenomena. How can that be improved to be more focused?