Are the number of atoms before and after a chemical reaction the same? Why?

Which of the following pressures is equal to 760 mm hg? 2.0 atm 101.3 pa 101,300 kpa 101,300 pa

Astudent made the lewis dot diagram of a compound shown. what is the error in the lewis dot diagram? a)an o atom should transfer all of its six electrons to mg because the formula is mgo b) both electrons of mg should be transferred to one o adam because the formula is mgo c) the electrons should be transferred from each o add him to capital mg because mg has fewer electrons d) the number of dots around mg should be four because it has to transfer two electrons to each o

List four observations that indicate that a chemical reaction may be taking place