1
JEE Main 2019 (Online) 10th January Evening Slot
+4
-1
Two kg of a monoatomic gas is at a pressure of 4 $$\times$$ 104 N/m2. The density of the gas is 8 kg/m3. What is the order of energy of the gas due to its thermal motion ?
A
104 J
B
103 J
C
105 J
D
106 J
2
JEE Main 2019 (Online) 10th January Evening Slot
+4
-1
An unknown metal of mass 192 g heated to a temperature of 100oC was immersed into a brass calorimeter of mass 128 g containing 240 g of water at a temperature of 8.4oC. Calculate the specific heat of the unknown metal if water temperature stabilizes at 21.5oC. (Specific heat of brass is 394 J kg–1 K–1)
A
458 J kg–1 K–1
B
1232 J kg–1 K–1
C
654 J kg–1 K–1
D
916 J kg–1 K–1
3
JEE Main 2019 (Online) 10th January Morning Slot
+4
-1
A heat source at T = 103 K is connected to another heat reservoir at T = 102 K by a copper slab which is 1 mthick. Given that the thermal conductivity of copper is 0.1 WK–1m–1, the energy flux through it in the steady state is -
A
200 Wm$$-$$2
B
65 Wm$$-$$2
C
120 Wm$$-$$2
D
90 Wm$$-$$2
4
JEE Main 2019 (Online) 10th January Morning Slot
+4
-1
Out of Syllabus
Three Carnot engines operate in series between a heat source at a temperature T1 and a heat sink at temperature T4 (see figure). There are two other reservoirs at temperature T2 and T3, as shown, with T1 > T2 > T3 > T4. The three engines are equally efficient if -

A
T2 = (T13T4)1/4;  T3 = (T1T43)1/4
B
T2 = (T1T4)1/2;  T3 = (T12T4)1/3
C
T2 = (T1T42)1/3;  T3 = (T12T4)1/3
D
T2 = (T12T4)1/3;  T3 = (T1T42)1/3
EXAM MAP
Medical
NEET