1. Any of several cultivars of Rheum x hybridum, often used in pies and crumbles from Barium, Rhodium, Rubidium, Uranium
Your answer:
2. The EU Earth Observation Programme named after a rather famous Renaissance mathematician and astronomer from Nickel, Erbium, Copper, Sulphur, Cobalt, Phosphorous
3. What I sincerely hope you have had at least one of, if not two or three by now from Neon, Actinium, Carbon, Vanadium, Iodine
4. The creatures that were meant to inhabit the sunlit uplands of Brexit from Oxygen, Radon, Nickel, Carbon, Sulphur, Uranium
5. Invented by Alfred Nobel from Nitrogen, Tellurium, Iodine, Dysprosium, Americium