Here are the atomic masses of hypothetical elements: X = 13.25 amu
Y = 69.23 amu
Z = 109.34 amu
What is the % composition by mass of Y in the hypothetical compound
with formula X2Y5Z3?
Enter your answer to two decimal places. Do not include the % sign, just
the numerical answer.

the answer would be b i believe

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.