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

Which set of characteristics best describes igneous rock? a) largest type of rock, made of organic matter, hardest type of rock b) least abundant type of rock, made of other rocks, made mostly of minerals c) found on all continents, contains wavy bands of stripes, contains fossils d) most abundant type in earth's crust, made of magma/lava, contains no fossils