1
JEE Main 2017 (Online) 8th April Morning Slot
+4
-1
Out of Syllabus
An engine operates by taking n moles of an ideal gas through the cycle ABCDA shown in figure. The thermal efficiency of the engine is : (Take Cv = 1.5 R, where R is gas constant)

A
0.24
B
0.15
C
0.32
D
0.08
2
JEE Main 2017 (Online) 8th April Morning Slot
+4
-1
An ideal gas has molecules with 5 degrees of freedom. The ratio of specific heats at constant pressure (Cp ) and at constant volume (Cv) is :
A
6
B
$${7 \over 2}$$
C
$${5 \over 2}$$
D
$${7 \over 5}$$
3
JEE Main 2017 (Offline)
+4
-1
A copper ball of mass 100 gm is at a temperature T. It is dropped in a copper calorimeter of mass 100 gm, filled with 170 gm of water at room temperature. Subsequently, the temperature of the system is found to be 75oC. T is given by: (Given : room temperature = 30oC, specific heat of copper = 0.1 cal/gmoC)
A
825oC
B
800oC
C
885oC
D
1250oC
4
JEE Main 2017 (Offline)
+4
-1
An external pressure P is applied on a cube at 0oC so that it is equally compressed from all sides. K is the bulk modulus of the material of the cube and $$\alpha$$ is its coefficient of linear expansion. Suppose we want to bring the cube to its original size by heating. The temperature should be raised by:
A
$${P \over {3\alpha K}}$$
B
$${P \over {\alpha K}}$$
C
$${3 \alpha \over {P K}}$$
D
3PK$$\alpha$$
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