What is the slope of the line $AB$ in the given graph?

Temperature is a measure of ...........

$A$ uniform thermometer scale is at steady state with its $0 \, cm$ mark at $20^{\circ} C$ and $100 \, cm$ mark at $100^{\circ} C$. The temperature of the $60 \, cm$ mark is ............. $^{\circ} C$.

The temperature at which the reading of a Fahrenheit thermometer will be double that of a centigrade thermometer is ........ $^\circ$.

The electrical resistance in ohms of a certain thermometer varies with temperature according to the approximate law:
$R = R_{0} [1 + \alpha (T - T_{0})]$
The resistance is $101.6 \; \Omega$ at the triple-point of water $(273.16 \; K)$,and $165.5 \; \Omega$ at the normal melting point of lead $(600.5 \; K)$. What is the temperature (in $K$) when the resistance is $123.4 \; \Omega$?

Oxygen boils at $-183^{\circ} C$. This temperature is approximately (in $^{\circ} F$)