Since orbital period depends on how far you are from the sun, planets closer to the sun have a orbital period less than one earth year.
These planets are Mercury and Venus
We can't use the nitrogen present in the atmosphere although 80% of the atmosphere consists of nitrogen only.We get this from the plants called as leguminous plants which can convert or fix atmospheric nitrogen into usable ones..
P=18000000/6 zeros. not sure how to do rest