  We present a systematic analysis of the extended X-ray emission discovered
around 35 FR II radio galaxies from the revised Third Cambridge catalog (3CR)
Chandra Snapshot Survey with redshifts between 0.05 to 0.9.
  We aimed to (i) test for the presence of extended X-ray emission around FR II
radio galaxies, (ii) investigate if the extended emission origin is due to
Inverse Compton scattering of seed photons arising from the Cosmic Microwave
Background (IC/CMB) or to thermal emission from an intracluster medium (ICM)
and (iii) test the impact of this extended emission on hotspot detection.
  We investigated the nature of the extended X-ray emission by studying its
morphology and compared our results with low-frequency radio observations
(i.e., $\sim$150 MHz), in the TGSS and LOFAR archives, as well as with optical
images from Pan-STARRS. In addition, we optimized a search for X-ray
counterparts of hotspots in 3CR FR II radio galaxies.
  We found statistically significant extended emission ($>$3$\sigma$ confidence
level) along the radio axis for $\sim$90%, and in the perpendicular direction
for $\sim$60% of our sample. We confirmed the detection of 7 hotspots in the
0.5 - 3 keV.
  In the cases where the emission in the direction perpendicular to the radio
axis is comparable to that along the radio axis, we suggest that the underlying
radiative process is thermal emission from ICM. Otherwise, the dominant
radiative process is likely non-thermal IC/CMB emission from lobes. We found
that non-thermal IC/CMB is the dominant process in $\sim$70% of the sources in
our sample, while thermal emission from the ICM dominates in $\sim$15% of them.
