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1. Raffinose
2. Rain water
3. Raspberry
4. Rb⁺, Rubidium
5. Resorcinol
6. Retinol, Vitamin A
7. Retinol acetate, Vitamin A acetate
8. Retinol palmitate, Vitamin A palmitate
9. Rhamnose
10. Ribitol
11. Riboflavin, Vitamin B₂
12. Ribonuclease
13. Ribose
14. River water
15. RNA, Ribonucleic acid
16. tRNA, Transfer ribonucleic acid
17. Rubber
18. Rubidium, Rb⁺
19. Rutinose