A substance is on its fifth half-life. Which approximates the percentages of radioactive and stable isotopes, respectively? 96.9%; 3.1% 3.1%; 96.9% 12.5%; 87.5% 87.5%; 12.5% Need an answer fast

How many molecules are in 128g of H2O?

A student notices dark clouds in the sky and that the playground is wet the student reasons that it rained which scientific skill describes the students reasoning A. classifying B. observing C. inferring D. predicting

How does the density of oceanic crust differ from that of continental crust? why is this difference important

Which elements have the most similar chemical properties? a. Be and Mg b. Ca and Br c. Cl and Ar d. Na and P

The gasification of coal is a method of producing methane by the following reaction. C (s) + 2H2 (g) → CH4 (g) ∆H=?

Why is water (H2O) considered the "universal solvent"?

Which notations represent hydrogen isotopes?

Which of the following statements is true? Question 5 options: Chemical reaction rates vary with the conditions of the reaction, but nuclear decay rates do not.

2 human activities that contribute to runoff into water systems

Which of the following is an example of geographic isolation? A. a population of salmon dies out because they cannot find food. B. a zebra with a long mane moves into a population of zebras with short manes. C.