Please answer the question and explain

How much energy is made when a pice of wood burns. how do you know

Compare and contrast physical changes with chemical changes.

Ageologist determines that a sample of a mineral can't be scratched by a steel nail but can be scratched by a masonry drill bit. based on this information, the sample mineral has to be softer than a. orthoclase. b. fluorite. c. apatite. d. corundum.