thermodynamics (27 jan) - Live Session - NEET 2020Contact Number: 9667591930 / 8527521718

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An ideal heat engine exhausting heat at 27°C have

40% efficiency. Then it takes heat from a reservoir at

(1) 127°C

(2) 227°C

(3) 327°

(4) 427°

Which is correct?

(1) In an adiabatic process pressure, volume and

temperature all changes

(2) An adiabatic process may be a fast process

(3) An adiabatic process may be a slow process

(4) An isothermal process is a fast process

The work done in an isothermal process in a

particular gas depends upon only

(1) Volume change

(2) Pressure change

(3) Change in internal energy

(4) On both (1) & (2)

Specific heat of a substance during isothermal

process is

(1) Infinite

(2) Zero

(3) Positive

(4) Negative

If the temperature of source & sink in heat engine is

at 1000 K & 500 K respectively, then efficiency

can be

(1) 20%

(2) 30%

(3) 50%

(4) All of these

$\frac{\mathrm{Slope}\mathrm{of}\mathrm{isothermal}\mathrm{curve}}{\mathrm{slope}\mathrm{of}\mathrm{adiabatic}\mathrm{curve}}$ is equal to

1. 1

2. $\frac{1}{2}$

3. $\mathrm{\gamma}$

4. $\frac{1}{\mathrm{\gamma}}$

In an adiabatic process, work done versus change of

temperature $\u2206$T is

According to the figure select the correct statement

(1) The work in this process greater than isothermal

process between A & B

(2) The corresponding V - T curve is a parabola

(3) Both (1) & (2) are correct

(4) Only (2) is correct

The volume and temperature graph is given in the figure below. If pressures for the two processes are different, then which one, of the following, is true?

1. | \(P_1=P_2\) and \(P_3=P_4\) and \(P_3>P_2\) |

2. | \(P_1=P_2\) and \(P_3=P_4\) and \(P_3<P_2\) |

3. | \(P_1=P_2\) \(=\) \(P_3=P_4\) |

4. | \(P_1>P_2\) \(>\) \(P_3>P_4\) |

In a thermodynamical system for a diatomic gas

V versus T graph is as shown below. The ratio of

heat absorbed to work done is

1. $\frac{7}{2}$

2. $\frac{2}{5}$

3. $\frac{3}{5}$

4. $\frac{5}{3}$

In isochoric process, which of the following is

correct?

n moles of an ideal gas is heated at constant pressure

from 50°C to 100°C, the increase in internal energy

of the gas is $\left(\frac{{\mathrm{C}}_{\mathrm{p}}}{{\mathrm{C}}_{\mathrm{v}}}=\mathrm{\gamma}\mathrm{and}\mathrm{R}=\mathrm{gas}\mathrm{constant}\right)$

1. $\frac{50\mathrm{nR}}{\mathrm{\gamma}-1}$

2. $\frac{100\mathrm{nR}}{\mathrm{\gamma}-1}$

3. $\frac{50\mathrm{n\gamma R}}{\mathrm{\gamma}-1}$

4. $\frac{25\mathrm{n\gamma R}}{\mathrm{\gamma}-1}$

In an adiabatic expansion of O2 gas the volume

increased by 1.0%, the percentage change in

pressure is

(1) 1.0%

(2) 0.7%

(3) 1.4%

(4) 1.7%

One mole of an ideal diatomic gas expands

adiabatically. Work done by the gas as its

temperature changes from T_{1} to T_{2} is

1. $\frac{5}{2}R\left({T}_{1}-{T}_{2}\right)$

2. $\frac{5}{2}R\left({T}_{2}-{T}_{1}\right)$

3. $\frac{3}{2}R\left({T}_{1}-{T}_{2}\right)$

4. $\frac{3}{2}R\left({T}_{2}-{T}_{1}\right)$

In an isochoric process of an ideal diatomic gas,

100 J heat is supplied. The work done by the gas is

(1) 100 J

(2) 60 J

(3) 40 J

(4) Zero

In an adiabatic process, work done by the gas is

15 R (R is gas constant). The increase in internal

energy of the gas is $\left(\mathrm{\gamma}=\frac{5}{3}\right)$

(1) 15 R

(2) –15 R

(3) 25 R

(4) –25 R

Gas within a closed chamber undergoes the

processes shown in the PV diagram. The net heat

added to the system during one complete cycle is

(1) 2 J

(2) –2 J

(3) 9 J

(4) – 9 J

A gas kept in an open vessel exposed to atmospheric

pressure is heated to double its temperature. If initially

there were n moles in the vessel, then the number of

moles in the vessel after heating will be

(1) Remain same

(2) Become half

(3) Become double

(4) Becomes 1.5 times

Which of the following graph represents adiabatic

expansion of a gas on V-T graph?

Figure shows P-V graph for an ideal gas. Select the

correct alternative.

(1) If AB is isothermal, AC may be adiabatic

(2) If AB is adiabatic, AC may be isothermal

(3) Both AB and AC are isothermal

(4) Both AB and AC are adiabatic

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