What is the percent composition of potassium in KNO3

38.6%

Explanation:

Molar mass of KNO3 is

=39+14+(16*3)

=53+48

=101 g/mol

Now

Percentage composition of potassium in KNO3 is=(atomic mass of K*no. of atoms)/molar mass of KNO3 *100%

%age composition of K= (39*1)/101 *100%

=0.386*100%

=38.6%

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.

4d^55s^1 ( third choice)