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

An exothermic reaction is conducted in an insulated calorimeter filled with water. the calorimeter is then sealed so that there is no heat exchanged between the contents of the container and the surrounding air. which of the following statements is true about the reaction?

Which real-world scenarios below represent physical and chemical changes? -running a car -exploding fireworks -mixing water and powdered drink mix -combining oil and vinegar to make salad dressing -taking aspirin for a headache -diluting bleach with water-digesting dinner-spreading peanut butter on bread

What overall charge must all compounds have