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 actions are part of the process of scientific inquiry? Check all that apply

Symbiosis is an interaction between two different organisms living in close physical association. The relationship between fleas and a dog is most similar to which of the following relationships?

David observed properties of four different compounds, only one of which is an ionic compound. his observations are shown in the chart. which is most likely the ionic compound? w x y z

Carbon, nitrogen, and water are recycled through ecosystems many times. Which one of these eventually breaks down completely?

What is the best definition of energy? A) the capacity to expert strength. B) the capacity to measure mass C) the capacity to do work D) the capacity to measure heat

Organize the items listed into the proper sequence of events for gas exchange. a: O2 is transported to cells by circulatory system. b: O2 is drawn into the lungs during inhalation. c: Cells use O2 and generate CO2. d: CO2 is exhaled.

Research about the reaction of baking soda and vinegar

What mass (in mg) does 2.63 moles of nickel have? 3.56 * 105 mg 1.54 * 105 mg 2.23 * 104 mg 129 mg?

Given the propane molecule C3H8 (g) ! a) What is the balanced equation for the combustion of propane in O2? (20 pts.) b) What is the standard enthalpy change ΔH0 for the reaction at 25°C? (20 pts.

Which of the following happens during a chemical change? Check all of the boxes that apply. One atom or more changes into atoms of another element. New substances with different properties are formed. Solids, liquids, or gases may form.