Give reasons for the following: -
a) Naphthalene balls kept in stored clothes in our homes disappear over a period of
time.
b) Perspiration or sweating keep our bodies cool on a hot day.
c) Desert cooler cools better on hot and dry day than on a rainy day.
d) The back of our palm feels cool when it is moistened with alcohol.
e) Gases highly compressible whereas solids are incompressible.
f) Water kept in an earthen pot becomes cool during summers.
g) Sponge is a solid but can be compressed.
h) Doctors advise to put strips of wet cloth on the forehead of a person having a high fever.
Answers
Answer:
Explanation:
Protect yourself and others by making these 6 simple precautions your new habits:
Clean your hands often
Cough or sneeze in your bent elbow - not your hands!
Avoid touching your eyes, nose and mouth
Limit social gatherings and time spent in crowded places
Avoid close contact with someone who is sick
Clean and disinfect frequently touched objects and surfaces
Answer:
a) Naphthalene or mothballs kept between clothes disappear over a period of time because naphthalene balls undergo sublimation and form naphthalene vapours, which disappear into the air.
b) perspiration or sweating help keep our body cool on a hot day because of due to evaporation because when the Sweat evaporates it gains energy from the surroundings of the environment and in this way the whole body becomes cool.
c) On a hot dry day, the amount of water vapour present in air is less. Thus, water present inside the desert cooler evaporates more, thereby cooling the surroundings more. That is why a desert cooler cools better on a hot dry day.
d) Alcohols have a tendency to evaporate rapidly or we can say that alcohols are volatile in nature. ... Hence, when back of your hand is moistened with alcohol then it actually absorbs heat from your hand, that is, endothermic reaction takes place and our hand feels cool.
e) Gasses are highly compressible because it is less dense than other states of matter. it's intermolecular force of attraction is less and it has more space between the molecules. Therefore, it is easy to compress gas. While, solids are almost incompressible.
f) The water kept in an earthen pot seeps into the small pores in the pot and evaporates from the surface of the pot. The heat required for evaporation is taken from water inside the pot, thus cooling the water stored inside. This is the reason why on hot summer days water remains cool in earthen pot