mars
the one that paul comes from
Earth has an ozone layer in atmosphere. It is present in the stratospheric region. Other planets which have oxygen in their environment might have ozone.Some planets like earth do. Others might have.
If by gas you mean an atmosphere, there are no planets with an atmosphere anywhere similar to Earth.
what planet's resources might come close with earth
Nobody knows for sure, but there is so many, that there might be more planets than people on earth!
Because they are like other life planets they might be able to produce more life when Earth explodes.
The geology of the Moon and the rock planets like Mars.
Life which does not originate from planet Earth may very well have developed on other planets. There is really no other explanation for where it would have come from.
planet A better answer might be "primary". Objects other than planets can have satellites.
They might. Just remember, the only (water) ice fields we know of are on satellites, not planets.
There have been a number of extrasolar planets discovered that might resemble Earth. However, due to the extreme recency of the technology, and even the idea that Earth might not be unique, there is very limited data from the search for habitable planets. On a more theoretical note, if you take into account the trillions of known and estimated galaxies, and the trillions of stars in most galaxies, and the number of those stars that have planetary systems orbiting them, and the number of those planetary systems orbiting in the habitable zone, the number of possible Earth-like planets is really astonishing.
that remains to be seen. although the chances are slim, there might be an earth-like planet millions of light-years away!