If an average person jogs, he produces \(14.5 \times10^3\) cal/min. This is removed by the evaporation of sweat. The amount of sweat evaporated per minute (assuming \(1\) kg requires \(580 \times10^3\) cal for evaporation) is:

Three copper blocks of masses \(M_{1} ,   M_{2} \) and \(M_{3}\) kg respectively are brought into thermal contact till they reach equilibrium. Before contact, they were at \(T_{1} ,   T_{2} ,   T_{3}   \left(\right. T_{1} > T_{2} > T_{3} \left.\right)\). Assuming there is no heat loss to the surroundings, the equilibrium temperature \(T\) is:
(\(s\) is the specific heat of copper)

1. \(T = \dfrac{T_{1} + T_{2} + T_{3}}{3}\)

2. \(T = \dfrac{M_{1} T_{1} + M_{2} T_{2} + M_{3} T_{3}}{M_{1} + M_{2} + M_{3}}\)

3. \(T = \dfrac{M_{1} T_{1} + M_{2} T_{2} + M_{3} T_{3}}{3 \left(\right. M_{1} + M_{2} + M_{3} \left.\right)}\)

4. \(T = \dfrac{M_{1} T_{1} s + M_{2} T_{2} s + M_{3} T_{3} s}{M_{1} + M_{2} + M_{3}}\)

Consider a cycle followed by an engine (figure). 

1 to 2 is isothermal,
2 to 3 is adiabatic,
3 to 1 is adiabatic.
Such a process does not exist, because:

Choose the correct alternatives: