Question

state noble gas whose electron configuration is attained in a lewis structure for hydrogen cyanide and noble gas attained in lewis structure for cyanogen?

I have answered this several times but at times it really wasn't an answer. I am not familiar with discussing MOLECULES that are isoelectronic with noble gases. I am familiar with ELEMENTS that attain noble gas configurations. H:C:::N: has 10 electrons total and your instructor may consider that the same as the noble gas structure for Ne BUT Ne has the 10 electrons total and HCN has 10 electrons in the outside shells only (valence electrons only). By the same argument, NCCN has 18 electrons and that is similar to Ar BUT, again, that is 18 electrons in the outside shell (valence electrons only) for (CN)2 while the 18 electrons in Ar are the total number of electrons (valence AND otherwise). If you want to talk about elements, then HCN has H attaining the He noble gas structure; C and N attain the Ne configuration. You must let your text and your notes be your guide as to how you use this information.

Thank you