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:
1. \(0.25\) kg
2. \(0.50\) kg
3. \(0.025\) kg
4. \(0.20\) kg

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 $T_1, T_2, T_3 (T_1>T_2>T_3)$. Assuming there is no heat loss to the surroundings, the equilibrium temperature \(T\) is: (\(s\) is the specific heat of copper)

1. $T=\frac{T_1+T_2+T_3}{3}$

2. $T=\frac{M_1{T}_1+M_2{T}_2+M_3{T}_3}{M_1+M_2+M_3}$

3. $T=\frac{M_1{T}_1+M_2{T}_2+M_3{T}_3}{3(M_1+M_2+M_3)}$

4. $T=\frac{M_1{T}_{1}s+M_2{T}_{2}s+M_3{T}_{3}s}{M_1+M_2+M_3}$

An ideal gas undergoes an isothermal process from some initial state i to
the final state $f$.

(a) dU = 0 

(b) dQ = 0 

(c) dQ = dU 

(d) dQ = dW

Choose the correct alternatives:

1. (a, b, c)

2. (a, d)

3. (b, c, d)

4. (a, c, d)

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:
1. (a, b)
2. (a, c)
3. (b, c)
4. (c, d)