What is called absolute zero temperature?

What is the value of the fixed point on the standard (Kelvin) scale?

What is the value of absolute zero temperature on the Fahrenheit scale?

$Assertion :$ In a pressure cooker,water is brought to a boil. The cooker is then removed from the stove. Now,upon removing the lid of the pressure cooker,the water starts boiling again.
$Reason :$ The impurities in water bring down its boiling point.

Temperature of water at the surface of a lake is $ -20^{\circ}C$. Then,the temperature of water just below the lower surface of the ice layer is ...... $^{\circ}C$.

If the temperature of a body increases by $30^{\circ}C$ on the Celsius scale,then the increase in temperature on the Fahrenheit scale is .... $^oF$.