Which of the following do ALL living things need in an ecosystem?

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

To find the enthalpy of a reaction in the lab, you measured the of the reactants and the change during the reaction.

Why do lunar and solar eclipse not happen every month