What is absolute zero temperature?

If the values of the temperature of a body in Fahrenheit and Celsius scales are in the ratio of $13:5$,then the temperature of the body is

$A$ centigrade and Fahrenheit thermometer are dipped in boiling water. The water temperature is lowered until the Fahrenheit temperature observed is $140^{\circ} F$. At that time the temperature registered by the centigrade thermometer is (in $^{\circ} C$)

$A$ scientist proposes a new temperature scale in which the ice point is $25 X$ ($X$ is the new unit of temperature) and the steam point is $305 X$. The specific heat capacity of water in this new scale is (in $J kg^{-1} X^{-1}$):

Maximum density of $H_2O$ is at temperature

It is difficult to cook rice in an open vessel by boiling it at high altitudes because of