Astudent while transferring the 2m solution of hcl into the calorimeter already containing the 2m solution of naoh splashed the upper sides of the cup. how would this error affect the final calculation for the heat of reaction?

The answer is a) carbon-12

It is a mixture. simply put, a compound must be pure, that is, of only one chemical structure and composition. a mixture is made of different chemical substances (i.e. elements, molecules, compounds) that are not chemically bonded to each other, but instead physically grouped together, as in the case of gasoline (a homogeneous solution).