The gases can be liquefied by

Which property of gas is used in supplying oxygen cylinders to hospitals?

Evaporation is called as

$(a)$ Define boiling point.
$(b)$ Express the boiling point of water in Celsius as well as Kelvin scale.
$(c)$ $A$ diver is able to cut through water in a swimming pool. Which property of matter does this observation show?

Which physical quantities are to be altered for liquefying gases?

$(a)$ State one similarity and one difference between evaporation and boiling.
$(b)$ Account for the following:
$(i)$ We wear cotton clothes in summer.
$(ii)$ $A$ wet handkerchief is placed on the forehead of a person suffering from high fever.
$(iii)$ Wet clothes dry slowly during the rainy season.