Marie Curie formulated the hypothesis that there exists a radioactive element distinct from uranium and barium, and she tested its implications. Her method was first applied to pitchblende, a substance that includes uranium and gives off high amounts of radioactivity. Curie isolated a white powder from the pitchblende that was 900 times more radioactive than pure uranium. But because the powder contained barium, an element that also produces radiation, the findings were not yet conclusive. Curie resorted to spectrographic analysis, which indicated that the substance was not barium. The evidence produced by all of these tests established the existence of another radioactive element that came to be known as radium. Which of the following statements properly describe the discovery of radium? A. Because barium and uranium were the only elements known to give off radiation and yet, in this case, they had to be eliminated as the source of an excess radiation, internal coherence required the hypothesis of an as yet unknown radioactive element.
B. Curie's spectrographic studies contradict the belief that she had discovered a substance that was neither uranium nor barium.
C. Spectrographic studies supported the coherence of the radium hypothesis.
D. The internal coherence of the hypothesis that established the existence of radium was achieved in part by the elimination of other known elements that cause radiation.

What is the important of the ten commandments?

What were some passive/non-direct ways that enslaved africans did to resist slavery?

Describe the location of the pyrenees: what are the 4 regions of the united kingdom: describe the danube river: describe the ural mountains: describe the location of the scandinavian peninsula: describe the european plain: describe the location of the alps: what are the effects of acid rain on germany’s black forest? what are the main causes of air pollution? how is the uk’s government is solving the air pollution problem? describe the effects of the nuclear explosion in chernobyl: describe the population distribution of russia: explain why russia’s natural resources are difficult to use: describe the slavic language family: describe the germanic language family: describe the romance language family: locate where all three religions originated: classify the three religions according to the date each began: list the holy book for each religion: exploration 1. prince henry the navigator is from which european country? 2. which 4 european countries had huge empires around the world? 3. which 4 european countries had colonies in the americas? 4. what religion did the early european explorers hope to spread? 5. where did christopher columbus land in 1492? 6. why was prince henry nicknamed “the navigator”? russian revolution 7. what type of government did czar nicholas ii have in russia? 8. what was one cause of the russian revolution? 9. what role did vladimir lenin play in the russian revolution? 10. what year did lenin bring communism to russia (soviet union)? treaty of versailles 11. what were the terms of the treaty? 12. why did france want the treaty to be harsh? world war ii 13. who was the leader of the nazi party in germany? 14. what happened to people who spoke out against hitler? 15. the holocaust occurred during which war? cold war 16. what are the dates of the cold war? 17. which two superpowers engaged in the cold war? 18. what was the purpose of the berlin wall? *locate portugal & germany on a map.