A body cools from $91°C$ to $89°C$ in $5$ minutes when the room temperature is $20°C$. How much time it will take to cool from $71°C$ to $69°C$ ?

The difference between the length of a certain brass rod and that of a steel rod is claimed to be constant at all temperatures. (Y/N)

The scale of temperature at which there's no negative reading is called .............. (fill in blank)