砷(As)是一种非金属元素,常见的化合价为-3、0、+3,常温下-3价不稳定,+3价稳定,砷化氢(AsH3)常温下能在空气中自燃.下列属于砷化氢自燃后的主要产物的是( )A. As2O3B. AsC. H2D.
"A direct measure of solar activity is the number of sunspots on the surface," Reinhold said. "Finding such stars with very similar parameters as our sun but being five times more variable was surprising." The sun -made up mainly of hydrogen and helium-is an average-...
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