At sea level, the atmospheric pressure is pounds per square inch.
a ) 15.5
b ) 13.7
c) 14.7
d ) 10

1. You need two points because changes in temperature changes are not constant across measurement units. For example, a change of 10° Celcius is different from a change in 10° Fahrenheit.

2a. I believe that this means that temperature scale is constant/proportional to the length of the thermostat.

i. 2 milimeters

ii. 218 milimeters