A physical change is exemplified by the ____________
A. burning of bush B. rusting of a metal C. dissolution of calcium in water D. heating of ammonium chloride
Correct Answer: D
Explanation
physical change, as you probably already know, is the one that is easily reversible. When ammonium chloride is heated, it changes into the gaseous form (sublimation). On getting to the cooler region of the tube, it changes back into the solid realm. What can you say about option C - "dissolution of calcium in water"? Majority of dissolutions are physical changes but this example flies in the face of them all! Calcium and other reactive metals, notably potassium and sodium react with water to produce