Answer: one molecule of O2.
Explanation: sweet i just took a guess but I believe that if 3 o2 molecules - 2 h2 molecules I think that its just basic maths and it is C because 3-2 = 1 and its o2 remaining, sorry if I’m wrong.
B, they belong to group 1
A: Li is period 2 and Na is period 3
C: Na has one more electron shell
D: Not related to how it is spelled
Answer: A gas molecules have high kinetic energy due to which they have move rapidly from one place to another
Explanation: