Here's the question: The CN molecule has been observed spectroscopically in comets where pressure has been estimated to be as low as 10–10 mm Hg. Draw a Lewis structure for CN. Suggest an explanation as to why this species can persist in a comet but is unstable under normal terrestrial conditions. The only progress I could make was to realize that CN is a free radical since it has 1 unpaired valence electron. And if I understand the question correctly, CN is stable under conditions of extremely low pressure but unstable at normal conditions of higher pressure, and its asking why this is, and I'm kind of clueless. Please help! Thanks.