Question

Assertion: Our palm feels cold when we put petrol on it.
Reason : During evaporation, particles of the liquid absorb energy from the surrounding or the surface of the palm to compensate for the loss of energy, making the surroundings cool.
A. Both assertion and reason are correct and reason is the correct explanation for assertion.
B. Both assertion and reason are correct but reason is not the correct explanation for assertion.
C. Assertion is correct but reason is incorrect
D. Both assertion and reason are incorrect

Answer 1

Hint: Evaporation is the process when the liquid substance changes the phase and converts into the gaseous phase as water vapors. The energy or the heat required to change the phase from liquid to gas is known as the latent heat of vaporization. Due to the vaporization of substances like acetone or petrol our palm gets cold.

Complete answer:
We have been given an assertion that our palm gets cold when we put petrol on it. The reason is that the petrol is a volatile liquid, as we put it on the greater area such as our palm, it starts evaporating. The evaporation is carried out by absorbing energy or heat from our palm. This gives our palm a cold sensation, as the absorption of energy is an endothermic reaction that creates a cooling effect.
Hence, the reason given is correct. So both assertion and reason are correct and reason is the correct explanation for assertion.

Thus, option A is correct.

Note:
The reactions where the reactants release energy in the process of the chemical change are called exothermic reactions that result in heat to be expelled as a by-product with negative enthalpy. On the other hand, endothermic reactions occur when the energy is absorbed, so they result in the cooling effect and the enthalpy is positive.