A physical change can be distinguished from a chemical change because during a physical change- a. the properties of the substance may change, but no new substances are produced b. the properties of the substance change for only a short time but will return to their original state. c. an entirely new substance with new properties forms as a result of the change d. a new substance is produced, but the new substance has properties identical to the original substance

For ai it's atomic number is 13 and it's mass number is 27 how many neutrons does it have

Mercury metal is poured into a graduated cylinder that holds exactly 22.5 ml the mercury used to fill the cylinder mass in 306.0 g from this information calculate the density of mercury

The picture represents the process that produces most of the energy used by living organisms on earth. which process is represented in the picture? a) the magnetic attraction between two hydrogen nuclei. b) the fusion of hydrogen nuclei to produce a helium nucleus in the core of the sun. c) the fission of hydrogen nuclei to produce a helium nucleus in the core of the sun. d) the chemical reaction between hydrogen nuclei to produce a helium nucleus in earth's atmosphere.