When solid potassium chlorate is strongly heated, it decomposes according to the balanced equation
2 KClO3(s) → 2 KCl(s) + 3 O2(g)
Which observation would provide the most convincing evidence that a chemical change has occurred?
a) The solid melts to form a clear, colorless liquid as the temperature increases.
b) The white solid turns a pale yellow as it is heated.
c) A gas is released that relights a glowing splint placed at the mouth of the test tube.
d) A glowing splint inserted into the gas is immediately extinguished.