Question

gerald’s science teacher mixed liquid x and liquid y, both at room-temperature, in a large beaker.
image of beakers with liquid x, liquid y, and their mixture
the mixture in the large beaker still looked clear like water, but when the students, one at a time, carefully touched the outside of the large beaker, it felt warm to the touch.
why did the large beaker most likely feel warm?
a. the two liquids were not soluble in water.
b. the release of a gas heated the solution.
c. the energy of mixing warmed the liquids.
d. a chemical reaction produced a new substance.

Explanation:

The mixture of liquids X and Y became warm. Option A is irrelevant (solubility in water isn’t mentioned). Option B is incorrect because no gas release is noted. Option C refers to physical mixing energy, but the key is that a temperature change often indicates a chemical reaction (which produces new substances, as in D). A chemical reaction can release heat (exothermic), causing the beaker to feel warm.

Answer:

D. A chemical reaction produced a new substance.