fourth period
The third period is similar to the second, except the 3s and 3p sublevels are being filled. Because the 3d sublevel does not fill until after the 4s sublevel, the fourth period contains 18 elements, due to the 10 additional electrons that can be accommodated by the 3d orbitals.
None of the above the answer would be D
Sorry but it depends on the gas in question and it's temperature of condensing /boiling point if this it 0° it will turn liquid