美国宇航局（NASA）马丽诺娃博士最近找到了一种比二氧化碳有效10 000倍的“超级温室气体”——全氟丙烷，并提出用其“温室化火星”，使火星成为第二个地球的计划。卤素在生产、生活及高科技中的应用越来越广泛。下列关于卤素（用X表示）的下列叙述正确的是（ ）
A.卤素单质与水反应均可用X2+H2O====HXO+HX表示
B.HX都极易溶于水，它们热稳定性随核电荷数增大而增强
C.卤素单质的颜色从F2I2按相对分子质量增大而加深
D.X-的还原性依次为：F-<Cl-<Br-<I-，因此相对分子质量小的卤素单质可将相对分子质量大的卤素从它的盐溶液里置换出来
答案：C
本题主要考查对卤素性质递变性的认识，此外还要掌握氟的特殊性。F2与水反应：2F2+2H2O====4HF+O2，A项错；HX极易溶于水，但其热稳定性随核电荷数增大而减弱，即HF>HCl>HBr>HI，B项错；F2不能将氯、溴、碘从它们的盐溶液中置换出来，而是先与水反应，D项错。
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| In 1990 my husband, Donald, and I were vacationing in Hawaii. Donald and I had been there many times over the years. The weather was 1 that day and we practically had the beach to ourselves. The 2 reached its top, close to shore, and I walked 3 into the surf, waiting for a breaker. Within seconds the huge waves knocked me off my 4 . My legs suddenly felt powerless. I thrust my arms up. "Help! Help!" My husband was on the beach with his 5 , ready to take a picture of me riding in on a breaker. "Donald!" I 6 , struggling to signal with my hands. He didn't 7 . He couldn't hear my cries. The few others on the beach were too far away. 8 I knew that if I swam with the current (洋流) I'd stay along the 9 , I panicked and fought to get 10 on the beach. I tried desperately to keep my head 11 water. But I couldn't get back to shore, no matter how hard I tried. Extremely 12 and out of breath, I looked up. A nice-looking young man was beside me He stood solidly, as if his feet were 13 in the ocean floor. How strong he 14 be, I thought. "Take my hand," he said, "and relax." I 15 for him and the next thing I knew I was 16 toward my husband. Donald held me tight, understanding at last that I had been 17 . "I'm so glad you're safe," he 18 . "Thanks to this young man," I said, 19 to introduce my rescuer. "He was here a second ago," Donald said. We looked 20 . No one was anywhere near US. | ||||
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