I don’t see what you need help with but thanks:)
Reactivity - Reactivity refers to how likely or vigorously an atom is to react with other substances. This is usually determined by how easily electrons can be removed (ionization energy) and how badly they want to take other atom's electrons (electronegativity) because it is the transfer/interaction of electrons that is the basis of chemical reactions.
Metals
Period - reactivity decreases as you go from left to right across a period.
Group - reactivity increases as you go down a group
Why? The farther to the left and down the periodic chart you go, the easier it is for electrons to be given or taken away, resulting in higher reactivity.
Non-metals
Period - reactivity increases as you go from the left to the right across a period.
Group - reactivity decreases as you go down the group.
Why? The farther right and up you go on the periodic table, the higher the electronegativity, resulting in a more vigorous exchange of electron
The other gas which the article mentioned is Helium gas.
<h3>What is Compression?</h3>
This refers to the squeezing or shortening of a substance which is most often done by increasing the temperature.
The information scientists hope to gain by compressing this gas into a solid is by studying the molecular structures and using it in the production of other substances which is why Nitrogen and Helium are the gases being studied in this scenario.
Read more about Compression here brainly.com/question/17266589
