Hium-235 has a half-life of 700 million years. How long does it take a 100- gram sample of Uranium-235 to decay to a mass of 50 grams?
A. 1,400 million years
B. 235 million years
C. 350 million years
D. 700 million years

The activity of the modern sample is 1.10 bq . how long does that measurement take?

Some steps in cell division are shown below: 1. chromosomes condense and pair up 2. segments of dna of sister chromatids twist and cross 3. exchange of dna occurs between chromosomes 4. four daughter cells are created that are haploid which of the following steps is least likely to occur during meiosis 1?

Put each tile to the correct location. categorize each term as something that is typical of a scientific theory, a scientific hypothesis, or both. 1) scientific theories 2) both 3) scientific hypothesis a). a tentative statement used to guide scientific investigations b). makes predictions about future events c). can be tested many independent researches d). based on observations of natural phenomena e) . a well-established highly reliable explanation