Magnesium oxide doesn't exist in gaseous form. It occurs naturally in mineral form - as periclase. In refined form - it is a white solid

Magnesium oxide, or magnesia, is a white hygroscopic solid mineral that occurs naturally as periclase and is a source of magnesium. It has an empirical formula of MgO and consists of a lattice of Mg²⁺ ions and O²⁻ ions held together by ionic bonding

According to SOWPODS (the combination of Scrabble dictionaries used around the world) there are 18 words with the pattern P-R----S-. That is, nine letter words with 1st letter P and 3rd letter R and 8th letter S. In alphabetical order, they are:

parablast

parcheesi

parsonish

periblast

periclase

periplasm

periplast

perkiness

personise

phrasiest

piroplasm

porkiness

porteress

porthouse

portliest

purpliest

pursiness

pyroclast

According to SOWPODS (the combination of Scrabble dictionaries used around the world) there are 25 words with the pattern P--I-L---. That is, nine letter words with 1st letter P and 4th letter I and 6th letter L. In alphabetical order, they are:

palillogy

panislams

papillary

papillate

papilloma

papillons

papillose

papillote

papillous

papillule

pavillons

penillion

periblast

periblems

periclase

pericline

perilling

periplasm

periplast

petillant

petiolate

petiolule

pupillage

pupillary

pupillate

According to SOWPODS (the combination of Scrabble dictionaries used around the world) there are 24 words with the pattern -ER-C----. That is, nine letter words with 2nd letter E and 3rd letter R and 5th letter C. In alphabetical order, they are:

ceraceous

cerecloth

feracious

ferocious

mericarps

merocrine

merycisms

pericarps

periclase

pericline

pericones

pericopae

pericopal

pericopes

pericopic

pericycle

reracking

rerecords

sericeous

sericites

sericitic

veracious

xerically

xerochasy