ack":"They have an even number of nucleons, resulting in zero nuclear spin.","points":1,"mcqOptions":[{"text":"They have an even number of nucleons, resulting in zero nuclear spin.","correct":true,"explanation":"Even numbers of nucleons give these nuclei a balanced nuclear arrangement with total nuclear spin of zero, so they cannot interact with the magnetic field in the way required to produce an NMR signal."},{"text":"They have an odd number of nucleons, resulting in non-zero nuclear spin.","correct":false,"explanation":"Odd nucleon numbers generally produce non-zero nuclear spin, so this reverses the relevant relationship. The correct explanation is that an even number of nucleons gives zero nuclear spin."},{"text":"They have an even number of electrons, resulting in zero nuclear spin.","correct":false,"explanation":"Nuclear spin depends on the combined arrangement of protons and neutrons, not on electron configuration. The even numbers of nucleons in these nuclei result in zero nuclear spin."},{"text":"They have an even number of protons, resulting in zero nuclear spin.","correct":false,"explanation":"An even number of protons alone does not explain the NMR behaviour. For these nuclei, the relevant feature is an even number of nucleons, which produces zero nuclear spin."}]},{"id":"a634de73-7877-4e19-bcd5-0901f1c12ed4","cardType":"basic","front":"Which two nuclei with non-zero spin are most commonly used to analyze organic structures?","back":"

Hydrogen-1 ($^{1}$H)
Carbon-13 ($^{13}$C)

","points":1,"mcqOptions":[{"text":"

Hydrogen-1 ($^{1}$H)
Carbon-13 ($^{13}$C)

","correct":true,"explanation":"Hydrogen-1 and carbon-13 both have non-zero nuclear spin and are sufficiently abundant for routine structural analysis, making them the standard nuclei in organic NMR spectroscopy."},{"text":"

Hydrogen-1 ($^{1}$H)
Carbon-12 ($^{12}$C)

","correct":false,"explanation":"Carbon-12 has zero nuclear spin because it contains an even number of nucleons, so it cannot give a conventional NMR signal. Carbon-13, not carbon-12, is the commonly analysed carbon isotope."},{"text":"

Fluorine-19 ($^{19}$F)
Phosphorus-31 ($^{31}$P)

","correct":false,"explanation":"Fluorine-19 and phosphorus-31 can be studied by NMR, but they are specialised nuclei rather than the standard pair used for most organic structural analysis. The usual pair is hydrogen-1 and carbon-13."},{"text":"

Hydrogen-2 ($^{2}$H)
Nitrogen-14 ($^{14}$N)

","correct":false,"explanation":"Deuterium and nitrogen-14 have non-zero spin, but they are not the most commonly used nuclei for routine organic structure determination. Hydrogen-1 and carbon-13 are the standard choices."}]}]}],"examCountdown":{"examDate":"2027-05-28","paperLabel":"Paper 1"},"heading":"Spectroscopy","title":"Spectroscopy Flashcards","topicSidebar":"$L40"}]}],"topicId":"b66a79fc-f949-55b1-b2b0-aaf104a3bbd3","walled":"$L41"}],"$L42"]