Uranium-238 decays very slowly. its half-life is 4.47 billion years.

What percentage of a sample of Uranium-238 will remain after 13.4 billion years?

i have to test after 3 days!

Which best describes two ways in which hydrogen is involved in photosynthesis? A) 1 - Hydrogen is stored in leaves of plants. 2 - Hydrogen combines with carbon dioxide to make glucose. B) 1 - Hydrogen is stored in leaves of plants.

1. Water is easily contaminated by both biological and chemical contaminants. Define and give 3 examples of each 2. What happens when you mix an acid and a base 3. How does ppm compare to ppb 4.

In which of these types of human societies do people use money earned through office work as a resource to obtain food? A. Hunter-gatherer B. Agricultural C. Administrative D. Industrial

In which stage of the cell cycle does the cell do a final check list before actually dividing.

Which of the followibg describes scientist

What is a scientific variable

What kind of reactions are redox reactions a. reactions involving substituting different isotopes b. reactions involving losing and gaining electrons c. reactions involving protons transferring between atoms d.

Determine the number of atoms in 1.75 ml of mercury. (the density of mercury is 13.5 g/ml.)

In the reaction A + B + C >> D, what are the products? A. C and D B. A and B C. A, B, C, and D D. A and C

Which of the following is true of a person with a high credit score?