The present work is a generalized extension of an earlier study (Paper I) of infrared diagnostics for compact H II regions by including spectroscopic tools (in addition to the earlier approach using the photometric & imaging information). Self-consistent radiation transfer (in spherical geometry) through the interstellar cloud, has been carried out to predict emergent spectrum originating from both the dust as well as the gas components. This also includes detailed predictions about the infrared fine structure line emission of several heavy elements (in different ionization stages). The effects of different exciting stars (O4, O7 and B0.5) and different radial profiles (r0, r-1 and r-2) of densities have been explored. All the models studied here correspond to a fixed outer physical dimension.
Diagnostically, the most useful (photometric as well as spectroscopic) information of the emergent spectrum from the compact H II regions, have been quantitatively identified. For ease of comparison, the model predictions have been expressed in terms of directly observable quantities through the instruments onboard ISO. The predictions about the continuum are expressed in terms of colours and the spectral line results are expressed as luminosities and line to local continuum contrasts (detectability).
The density distribution
is well understood, by some of the colours presented here.
In the absence of any information regarding the optical
depth of the H II region, the colour-colour plots presented
here, provide useful information about the spectral type
of the embedded star as
well. The ratio of the radio continuum to the
FIR flux density, found to be the
most sensitive to 
100
for r-1 distribution, contains
useful information about the stellar type and also
density distribution of the H II region. The angular sizes
are also diagnostically very important.
The luminosity of fine structure lines are shown to be
extremely rich in information about the geometric and
physical details of the H II regions.
The results of the present study and the Paper I, would be extremely useful, for statistical studies on huge sample of data, from the space mission ISO, expected to be publicly available in the near future. It also presents a very general method of modelling, which can be used very efficiently for individual compact H II regions.
It is a pleasure to thank D. Narasimha for many useful discussions.