Metallic I’m pretty sure. :)
Answer:
INNER PLANTS
Mercury - Rocky planets
Venus - Rocky planets
Earth - Rocky planets
Mars - Rocky plants
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OUTER PLANETS
Jupiter - gas giants
Saturn - gas giants
Uranus - gas giants
Neptune - gas giants
The answer is (4) K+ and HSO4- ions, because the two radical ions bond to create KHSO4.
It also makes sense chemically speaking, because KH+ and SO4^2- cannot create a non-charged molecule, and naturally speaking all compounds that are not ions want to balance out their charges.