  Recent work on metal-intermediate globular clusters (GCs) with [Fe/H]=$-1.5$
and $-0.75$ has illustrated the theoretical behavior of multiple populations in
photometric diagrams obtained with the James Webb Space Telescope (JWST). These
results are confirmed by observations of multiple populations among M-dwarfs of
47 Tucanae. Here, we explore the multiple populations in metal-poor GCs with
[Fe/H]=$-$2.3. We take advantage of synthetic spectra and isochrones that
account for the chemical composition of multiple populations to identify
photometric diagrams that separate the distinct stellar populations of GCs. We
derived high-precision photometry and proper motion for main-sequence stars in
the metal-poor GC M 92 from JWST and Hubble Space Telescope (HST) images. We
identified a first generation (1G) and two main groups of second-generation
stars (2G$_{\rm A}$ and 2G$_{\rm B}$) and investigated their kinematics and
chemical composition. We find isotropic motions with no differences among the
distinct populations. The comparison between the observed colors of M 92 stars
and the colors derived by synthetic spectra reveals that helium abundance of
2G$_{\rm A}$ and 2G$_{\rm B}$ stars are higher than that of the 1G by $\Delta Y
\sim 0.01$ and $0.04$, respectively. The $m_{\rm F090W}$ vs. $m_{\rm
F090W}-m_{\rm F277W}$ color-magnitude diagram shows that below the knee, MS
stars exhibit a wide color broadening due to multiple populations. We constrain
the amount of oxygen variation needed to reproduce the observed MS width, which
is consistent with results on red-giant branch stars. We conclude that multiple
populations with masses of $\sim$0.1-0.8$M_{\odot}$ share similar chemical
compositions.
