Which of the following has the most thermal energy? 500 mL water at 25 degree celius, 1.5 L water at 25 degrees celius, 15 L water at 25 degrees celius

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).

The phase where ice changes directly to gas is called sublimation 

Answer the same molecular formula;

Ahigh energy (high speed) particle (alpha or beta or neutron) are shot at the target;