Two bodies A and B are kept in thermal contact. Heat capacity of A increases with temperature and is initially at 100°C while temperature of B is initially at 0°C. Then the final common temperature is

Here body A is hotter and body B is colder. So body A loses heat and body B gains heat. In this process, thermal capacity of body A deceases. So, we can say average thermal capacity of body A is lesser than that of body B.

By principle of calorimetry,

${\left(m_A{c}_A\right)}_{avg}\left(∆{\theta }_A\right)=\left(m_B{c}_B\right)\left(∆{\theta }_B\right)$

Since ${\left(m_A{c}_A\right)}_{avg}<\left(m_B{c}_B\right)$, therefore, $∆{\theta }_A>∆{\theta }_B$

Body A loses more temperature than what body B gains. So, final common temperature is $<{50}^0\mathrm{C}\text{ but }>0^0\mathrm{C}$