Students of different ages were given the samepuzzle to put together. The time it took eachstudent to complete the puzzle was compared.

the correct answer to this question is 2

chemical changes occur when a substance combines with another to form a new substance, called chemical synthesis or, alternatively, chemical decomposition into two or more different substances. these processes are called chemical reactions and, in general, are not reversible except by further chemical reactions. some reactions produce heat and are called exothermic reactions and others may require heat to enable the reaction to occur, which are called endothermic reactions. understanding chemical changes is a major part of the science of chemistry.

the objects have the same charge is correct.

nathan lee

gasoline is a mixture. it contains several different kinds of compounds that can be present in a variety of ratios.