A scientist finds a 200 gram rock composed of 150 grams of Lead-207 and 50 grams of Uranium-235. They know that the rock used to be entirely made of Uranium-235. The half-life of U-235 is 700 million years. How old is the rock?

Which best describes red blood cells? a. they are colorless b. they protect against disease-carrying microorganisms c. they transport oxygen throughout the body d. they aid in blood clotting

Ascientist discovers a new body between the orbit of neptune and the kuiper belt. the object is round and travels in an orbit around neptune with other space objects. the scientist claims that she has found a new dwarf planet. where is the scientist’s error?

Explain how organisms could be harmed by high levels of salt from roadways?