What is an endothermic reaction? what is an endothermic reaction? it is a reaction where there is a net adsorption of energy from a reaction. it is a reaction that requires heat as a reactant. it is a reaction where the products have more energy than the reactants. all of the above none of the above?

10. according to the law of conservation of mass, how does the mass of the products in a chemical reaction compare to the mass of the reactants?

Look at the spectrums of a star moving towards earth and a motionless star. which of these is a correct inference that can be draw from the observation of the two spectrums? (2 points) the spectrum of a motionless star is difficult to be viewed separately using oridinary telescopes. the spectrum of a motionless star is identical to the spectrum of a star which moves towards earth. the spectrum of a star shifts towards the red region when the star moves towards earth. the spectrum of a star shifts towards the blue region when the star moves towards earth.

About 3% of the water on earth is freshest. only about 40% of that freshwater is available for human use. why is so much freshwater unavailable for human use?