A student determines the density of an irregularly shaped block of lead in the laboratory. The displacement volume measured 25.2 mL using a graduated cylinder. The mass on the electric balance reads 285.768 g. What is the density of lead reporting to the appropriate number of significant figures allotted by the equipment used?

because u need two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei to form isotopes.

so since they all have the same shape? i mean maybe because m& m and reeses are both chocolates

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.