Practice question

Enriching methyl chloride with 100 percent carbon-13 replaces spin-zero 12C with magnetic I equals one-half nucleus, active in NMR. Protons directly bonded to 13C experience heteronuclear one-bond coupling 1JCH, splitting proton resonance into doublet following n+1 rule where n equals one magnetic neighbor. Remaining 12CH3Cl molecules still show central singlet. This pair of satellites flanking main peak demonstrates heteronuclear splitting, foundational for HSQC and HMQC editing that separates labeled from unlabeled pools, crucial for isotope tracing in metabolism and protein backbone assignments.