1
JEE Main 2019 (Online) 12th January Morning Slot
+4
-1
A cylinder of radius R is surrounded by a cylindrical shell of inner radius R and outer radius 2R. The thermal conductivity of the material of the inner cylinder is K1 and the of the outer cylinder is K2. Assuming no loss of heat, the effective thermal conductivity of the system for heat flowing along the length of the cylinder is :
A
K1 + K2
B
$${{{K_1} + 3{K_2}} \over 4}$$
C
$${{{K_1} + {K_2}} \over 2}$$
D
$${{2{K_1} + 3{K_2}} \over 5}$$
2
JEE Main 2019 (Online) 12th January Morning Slot
+4
-1
For the given cyclic process CAB as shown for a gas, the work done is :

A
1 J
B
10 J
C
5 J
D
30 J
3
JEE Main 2019 (Online) 11th January Evening Slot
+4
-1
Two rods A and B of identical dimensions are at temperature 30°C. If A is heated upto 180oC and B upto ToC, then the new lengths are the same. If the ratio of the coefficients of linear expansion of A and B is 4 : 3, then the value of T is
A
200oC
B
270oC
C
230oC
D
250oC
4
JEE Main 2019 (Online) 11th January Evening Slot
+4
-1
When 100 g of a liquid A at 100oC is added to 50 g of a liquid B at temperature 75oC, the temperature of the mixture becomes 90oC. The temperature of the mixture, if 100 g of liquid A at 100oC is added to 50 g of liquid B at 50oC, will be :
A
60oC
B
70oC
C
85oC
D
80oC
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