Electromagnetically decreases when the elements are considered in order of increasing atomic number.
In this problem they were asking regarding group 17.
Final answer: Electromagnetically
One way of knowing that oxygen was the gas removed from the volume of air and not another is to know what the volume of air is made of first. When the composition of the volume of air is already identified, then next would be the process of separating these elements from each other and as to which is to be separated first. This would usually lead to knowing their masses, their boiling and freezing points, the temperatures at which they condense, and so on. This is to identify their differences to each other and use those differences to successfully separate those elements to each other.
It can be more effective in liquids.
