What is thermal equilibrium?
a. When two objects in contact with each other are at the same pressure, they are said to be in thermal equilibrium.
b. When two objects in contact with each other are at different temperatures, they are said to be in thermal equilibrium.
c. When two objects in contact with each other are at the same temperature, they are said to be in thermal equilibrium.
d. When two objects not in contact with each toerh are at the same pressure, they are said be in thermal equilibrium.