Which of the following statements holds true for chemical change?

a) in a chemical change, no new substance is formed
b) in a chemical change, a substance changes its phase
c) in a chemical change, the molecular structure of a substance changes
d) in a chemical change, one substance dissolves into another

High-pressure liquid chromatography (hplc) is a method used in chemistry and biochemistry to purify chemical substances. the pressures used in this procedure range from around 500 kilopascals (500,000 pa) to about 60,000 kpa (60,000,000 pa). it is often convenient to know the pressure in torr. if an hplc procedure is running at a pressure of 1.03×108 pa , what is its running pressure in torr?