Marie Curie studied the radiation of all compounds containing the known radioactive elements, including uranium and thorium, which she later discovered was also radioactive. She also found out that:
- you can exactly measure the strength of the radiation from uranium;
- the intensity of the radiation is proportional to the amount of uranium or thorium in the compound - no matter what compound it is;
- the ability to emit radiation does not depend on the arrangement of the atoms in a molecule; it must be linked to the interior of the atom itself - a revolutionary discovery!
When she realized that some uranium and/or thorium compounds had stronger radiation than uranium, she made the following hypothesis: there must be an unknown element in the compound which had a stronger radiation than uranium or thorium. Her work aroused the interest of her husband, Pierre Curie, who stopped his own research on crystals and joined the "detective work" with his wife. And Marie was proven right: in 1898 the Curies discovered two new radioactive elements: radium (named after the Latin word for ray) and polonium (named after Marie's home country, Poland).
1. The Soviet Union controlled everything people bought and sold and the United States let people have some type of freedom like to own land and businesses and compete for themselves
2. The cold war began after the surrender of Nazi Germany in 1945, when the uneasy alliance between the United States and Great Britian on the one hand the Soviet Union on the other started to fall apart. The Americans and the British worried that the Soviet domination in eastern Europe might be permanent
3. Containment
4. A program providing aid to Western Europe following devastation of World War 2
8. An important development in the Cold war because it was the first time the two superpowers, United States and the Soviet Union, had fought a proxy war in a third country. The proxy war or limited war strategy would be feature pf other Cold War conflicts for example Vietnam War
Answer:
Shay's rebellion highlighted these problems by showing that the Articles of Confederation was not able to handle crisis well. It had no sympathy for the war veterans of the Revolutionary War who had to take out loans as they were off fighting. It showed that the U.S. had failed to protect and see the side of those in need.
Answer: A
Explanation:
they used astronmy to to develop calendars based based on the movement of stars and planets. B, C, and D are incorrect.
