Question

Two bodies A, B and bodies B, C are in thermal equilibrium with each other. The temperature of A is ${45}^{\circ }\text{C}$. Then the temperature of C is

• A. ${45}^{\circ }\text{C}$
• B. $<{45}^{\circ }\text{C}$
• C. $>{45}^{\circ }\text{C}$
• D. can be any temperature

Answer 1

The correct option is A ${45}^{\circ }\text{C}$

According to zeroth law of thermodynamics, if two thermodynamic systems are in thermal equilbrium with a third one individually, then they are in thermal equilibrium with each other.
Accordingly, thermal equilibrium between systems is transitive relation. So, If A, B and B, C are in thermal equilbrium & temperature of A is given as ${45}^{\circ }\text{C}$, then C must be at ${45}^{\circ }\text{C}$ temperature as well.
Thus, option (a) is the correct answer.