  We study the capabilities of Lyman $\beta$ and the O I 1027 and 1028 \AA\
spectral lines for understanding the properties of the chromosphere and
transition region. The oxygen transitions are located in the wing of Lyman
$\beta$ that is a candidate spectral line for the solar missions Solar
Orbiter/SPICE and Solar-C (EUVST). We examine general spectroscopic properties
of the three transitions in the quiet Sun by synthesizing them assuming
non-local thermal equilibrium taking into account partial redistribution
effects. We estimate the heights where the spectral lines are sensitive to the
physical parameters computing the response functions to temperature and
velocity using a 1D semi-empirical atmospheric model. We also synthesize the
intensity spectrum using the 3D enhanced network simulation computed with the
BIFROST code. The results indicate that Lyman $\beta$ is sensitive to the
temperature from the middle chromosphere to the transition region while it is
mainly sensitive to the line-of-sight velocity at the latter atmospheric
layers, around 2000 km above the optical surface. The O I lines form lower in
the middle chromosphere, being sensitive to the LOS velocities at lower heights
than those covered by Lyman $\beta$. The spatial distribution of intensity
signals computed with the BIFROST atmosphere, as well as the inferred
velocities from the line core Doppler shift confirm the previous results.
Therefore, these results indicate that the spectral window at 1025 \AA\
contains several spectral lines that complement each other to seamlessly trace
the thermal structure and gas dynamics from the middle chromosphere to the
lower transition region.
