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).
Answer:
the first duties was to teach religion make converts and hold mass on sundays
Answer:
Choices
Explanation:
Due to limited resources in a our wold, people have to make do with choices because it is nearly impossible to have all what we want.
The two main problems in economics revolves round:
Limited resources
Unlimited wants
The cost of choosing one item over another and forgoing it is called the opportunity cost.
Choices are often made by drawing up a scale of preference from which the most pressing needs can first be attended to.
If there are enough resources, there wouldn't be a need to make choices when demanding for certain goods and services.
If the general assembly approves it, the United Nations can send in "peacekeepers" to ensure cease-fires in conflict areas, although the effectiveness of this tactic is in dispute.
