The top five, for the most part, make sense. The U.K, what with more or less singlehandedly leading the Western Industrial Revolution, discovered most of the basic elements. Germany and Franc followed close behind, and the U.S. and Russia have been making more discoveries recently, like the newly named oganesson and tennesine, nos. 117 and 118 on the table. But why is Sweden so high? It's not because of high population or cold climate - it's because of the strange island of Ytterby, whose mine produced a staggering seven elements on the periodic table. Never heard of Ytterby? Good. Its population is a scant 0. At least, that's what census results show...anyway, Ytterby's mine was home to the discoveries of ytterby, yttrium, terbium, and erbium (all named for the town) as well as holmium, thulium, and gadolinium (respectively, for Stockholm, a mythological name of Sweden, and Gadolin, discoverer of the elements). And all by itself, tiny little Ytterby bumps Sweden from fifth to second!
I have no idea what Switzerland is doing in the answers here. It doesn't seem to have anything to do with the discovery of Hafnium.
My best guess is that the quiz setter got the (somewhat similar) flags of Switzerland and Denmark confused? 🤷♂️
Denmark is getting short shrift on this quiz... 😒