National and Regional Contests USA Contests USA Physics and Chemistry Contests National Chemistry Olympiad 2008 National Chemistry Olympiad 1 2008 USNCO Local #1: Liquid element Problem Statement Which element is a liquid at 2 5 ∘ C 25^\circ\text{C} 2 5 ∘ C 1.0 atm 1.0 \text{ atm} 1.0 atm < s p a n c l a s s = ′ l a t e x − b o l d ′ > ( A ) < / s p a n > bromine < s p a n c l a s s = ′ l a t e x − b o l d ′ > ( B ) < / s p a n > krypton < s p a n c l a s s = ′ l a t e x − b o l d ′ > ( C ) < / s p a n > phosphorus < s p a n c l a s s = ′ l a t e x − b o l d ′ > ( D ) < / s p a n > xenon <span class='latex-bold'>(A)</span>\hspace{.05in}\text{bromine} \qquad<span class='latex-bold'>(B)</span>\hspace{.05in}\text{krypton} \qquad<span class='latex-bold'>(C)</span>\hspace{.05in}\text{phosphorus} \qquad<span class='latex-bold'>(D)</span>\hspace{.05in}\text{xenon} \qquad < s p an c l a ss = ′ l a t e x − b o l d ′ > ( A ) < / s p an > bromine < s p an c l a ss = ′ l a t e x − b o l d ′ > ( B ) < / s p an > krypton < s p an c l a ss = ′ l a t e x − b o l d ′ > ( C ) < / s p an > phosphorus < s p an c l a ss = ′ l a t e x − b o l d ′ > ( D ) < / s p an > xenon