Radical	Reaction Rate	Ribonucleic Acid
Radioactive Dating	Reactions Type	Ribosomal RNA
Radius Ratio	Reduction	Ring Silicate
Raoult's Law	Refractory	Rock Dating
Rare Earth Element	Repeated Twin	Rockwell Hardness Scale
Rate Determining Step	Representative Element	Romanechite
Rate Law	Resonance Hybrid	Rutile
Reaction Enthalpy	Reversible Reaction	Rutile Structure
Reaction Mechanism	Rhodochrosite