Question

1. Burning a candle is a chemical change. What is the primary evidence that burning the candle is a chemical reaction?

Answer 1

Answer 1) Option B) Temperature Change

Explanation :

The burning of candle is the reaction where both physical and chemical changes occurs. A physical change where the melted wax is cooled and the wax is obtained again. Whereas the chemical change takes place when the wick of the candle burns using the oxygen in the air and produces heat and light. So, this change in temperature is a chemical change as the burning process cannot be reverse, from the burnt  products like soot, smoke and carbon dioxide. Therefore, the temperature change is the evidence of a chemical change in the burning of candle.

Answer 2) Option B) It is a chemical change because heat energy is absorbed and the pack gets colder.

Explanation :

When Clara is mixing the vial contents the ice pack gets colder. On application of the ice pack on the injured area absorbs the heat from that region and becomes more colder. This happens because in the ice pack was the medium for the temperature change that was occurring. This temperature change by absorbing heat getting colder is the evidence of a chemical change.