JEE Main 2021 (Online) 25th July Evening Shift | Heat and Thermodynamics Question 112 | Physics

JEE Main 2021 (Online) 25th July Evening Shift

MCQ (Single Correct Answer)

-1

A heat engine has an efficiency of $${1 \over 6}$$. When the temperature of sink is reduced by 62$$^\circ$$C, its efficiency get doubled. The temperature of the source is :

124$$^\circ$$C

37$$^\circ$$C

62$$^\circ$$C

99$$^\circ$$C

JEE Main 2021 (Online) 25th July Evening Shift

MCQ (Single Correct Answer)

-1

Two spherical soap bubbles of radii r₁ and r₂ in vacuum combine under isothermal conditions. The resulting bubble has a radius equal to :

$${{{r_1}{r_2}} \over {{r_1} + {r_2}}}$$

$$\sqrt {{r_1}{r_2}} $$

$$\sqrt {r_1^2 + r_2^2} $$

$${{{r_1} + {r_2}} \over 2}$$

JEE Main 2021 (Online) 25th July Morning Shift

MCQ (Single Correct Answer)

-1

For a gas C_P $$-$$ C_V = R in a state P and C_P $$-$$ C_V = 1.10 R in a state Q, T_P and T_Q are the temperatures in two different states P and Q respectively. Then

T_P = T_Q

T_P < T_Q

T_P = 0.9 T_Q

T_P > T_Q

JEE Main 2021 (Online) 25th July Morning Shift

MCQ (Single Correct Answer)

-1

A monoatomic ideal gas, initially at temperature T₁ is enclosed in a cylinder fitted with a frictionless piston. The gas is allowed to expand adiabatically to a temperature T₂ by releasing the piston suddenly. If l₁ and l₂ are the lengths of the gas column, before and after the expansion respectively, then the value of $${{{T_1}} \over {{T_2}}}$$ will be :

$${\left( {{{{l_1}} \over {{l_2}}}} \right)^{{2 \over 3}}}$$

$${\left( {{{{l_2}} \over {{l_1}}}} \right)^{{2 \over 3}}}$$

$${{{l_2}} \over {{l_1}}}$$

$${{{l_1}} \over {{l_2}}}$$

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