What was one important discovery that the Curies made? O A material's radioactivity cannot be changed by altering the material physically
O A material's radioactivity can be weakened or intensified by changing it chemically.
O Radioactive materials generally contain radium or polonium.
O Radioactive materials are found only in the form of salts.

Which of the following is an example of physical change not a chemical change? a) a log gives off heat and light as it burns. b) a tree stores energy from the sun in its fruit. c) a penny lost in the grass slowly changes color. d) a water pipe freezes and cracks on a cold night.

Need , hurry pls create a superhero out of the element iron, what are its powers and his sidekick ( an element that works well with iron). how was the superhero made and who discovered him

Can anyone explain 1. review your spectrometry data and use the known elements to identify the star's composition. which unknown elements make up this star? justify your element selections. 2. in parts i and ii of the lab, what happened to the electrons of each element to produce the different colors of light? explain your answers using important terms from the lesson and information provided in the laboratory. 3. stars composed of heavier (more massive) elements are often slightly older than stars made predominantly from hydrogen and helium. based on your data, is the newly discovered star a younger star? explain your answer.