Answer: Option (c) is the correct answer.
Explanation:
Entropy is defined as the degree of randomness. This means that more is the number of collisions taking place between atoms of a substance more will be the randomness.
Therefore, more will be the entropy of substance. We cannot measure the entropy but we can measure the change in entropy of a substance.
A thermometer is a glass tube that contains a liquid column generally mercury, and it is usually used to measure the temperature of human body.
A calorimeter is a device or apparatus that is used in a chemical reaction to measure the amount of heat involved.
Therefore, we can conclude that the student can't measure entropy directly, only an entropy change.
Phenolphthalein is often used as an indicator in acid–base titrations. For this application, it turns colorless in acidic solutions and pink in basic solutions. Phenolphthalein is slightly soluble in water and usually is dissolved in alcohols for use in experiments.