It is made by bonding nitrogen dioxide molecules together in pairs.
ɪ t WORD_BOUNDARY ɪ z WORD_BOUNDARY m eɪ d WORD_BOUNDARY b aɪ WORD_BOUNDARY b ɑ n d ɪ ŋ WORD_BOUNDARY n aɪ t ɹ ə d̠ʒ ə n WORD_BOUNDARY d aɪ ɑ k s aɪ d WORD_BOUNDARY m ɑ l ɪ k j uː l z WORD_BOUNDARY t ə ɡ ɛ ð ə ɹ ɹ WORD_BOUNDARY ɪ n WORD_BOUNDARY p ɛ ɹ z WORD_BOUNDARY