Question $1(2\mathrm{.}5$ points$)$ Which of the following statements is true? Ultra$-$violet radiation can be used to cause spinning nuclei in the presence of an external magnetic field $($Bo$)$ to flip directions The chemical shift of a nucleus is reported in Hz$,$ and chemical shifts can only be compared when measured with identical instruments. If peak A is downfield of peak B$,$ peak A is to the right of peak B$.$ The energy difference between nuclear spin states is extremely large. In the presence of an external magnetic field $($Bo$),$ more nuclei occupy the lower energy state in which their spins are aligned with the magnetic field.