In a thermostat, what property of the bimetallic coil allows it to contract and expand? the two metals absorb different amounts of thermal energy. the two metals are placed perpendicular to each other. the two metals burn at different temperatures. the two metals turn into liquids when absorbing energy.

Hello!

In a thermostat, the property of the bimetallic coil that allows it to contract and expand is that The two metals absorb different amounts of thermal energy. 

This bimetallic coil is used to transform thermal energy into mechanical movement. Two metals with different thermal expansivity are joined together parallelly and the changes of temperature cause bending in different directions depending on if the temperature is rising or descending. 

The differences in the thermal energy absorption of the two metals are the basis for the mechanism of this device.