Answer:
The Answer is A) Metal X aluminium; Metal Y platinum
Step-by-step explanation:
The behavior of the bimetallic strip depends on the coefficient of thermal expansion. Where the coefficient of the metal X should be greater than the coefficient of thermal expansion for metal Y. In the attached image we can see the effect of this particular behavior.
In the only case where the coefficient of thermal expansion of the metal X is greater than the used in the metal Y is in case A.
Here we have:
![\alpha _(alum)=25*10^(-6) [1/C]\\ \alpha _(plat)=9*10^(-6) [1/C]\\\\alpha _(copp)=17*10^(-6) [1/C]\\\\alpha _(steel)=1*10^(-6) [1/C]\\](https://img.qammunity.org/2020/formulas/physics/middle-school/jabpsioeadi3v4zg159tpfwvi6so4y8mdb.png)