Tag: physics

Questions Related to physics

The SI unit for the coefficient of cubical expansion is

physics kinetic theory of gases thermal expansion in gases thermal expansion of fluids volume elasticity constant of gases

  1. $^\circ C$

  2. $per^\circ C$

  3. $cm^{2}/^\circ C$

  4. none of these

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Correct Option: D
Explanation:
The SI unit of coefficient of cubical expansion is $K^{-1}$
$\gamma =\cfrac { 1 }{ V } \cfrac { dV }{ dT } =\cfrac { 1 }{ { metre }^{ 3 } } \cfrac { { metre }^{ 3 } }{ K } ={ K }^{ -1 }$

Consider an expanding sphere of instantaneous radius R whose total mass remains constant. The expansion is such that the instantaneous density $\rho$ remains uniform throughout the volume. The rate of fractional change in density $\left(\dfrac{1}{p}\dfrac{d\rho}{dt}\right)$ is constant. The velocity v of any point on the surface of the expanding sphere is proportional to.

physics kinetic theory of gases thermal expansion in gases thermal expansion of fluids volume elasticity constant of gases

  1. R

  2. $R^3$

  3. $\dfrac{1}{R}$

  4. $R^{2/3}$

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Correct Option: A
an ideal gas is expanding such that $PT^2$ $=costant$ The coefficient of volume expansion of the gas is__? 
physics kinetic theory of gases thermal expansion in gases thermal expansion of fluids volume elasticity constant of gases

  1. $1|T$

  2. $2|T$

  3. $3|T$

  4. $4|T$

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Correct Option: C

Hydrogen is a diatomic gas. Its molar specific heat at constant volume is very nearly

physics kinetic theory maxwell-boltzmann speed distribution function behavior of perfect gas and kinetic theory kinetic theory of matter

  1. $\frac { 3 R } { 2 }$

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

  3. $\frac { 7 R } { 2 }$

  4. (b) or (c) depending on the temperature.

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Correct Option: D

$T _1$ is the temperature of oxygen enclosed in a cylinder. The temperature is increased to $T _2$ and Maxwellan distribution curves for $O _2$ at temperature $T _1$ and $T _2$ are plotted. If $A _1$ and $A _2$ are the areas under the curves and the speed axis, in both cases , then 

physics kinetic theory maxwell-boltzmann speed distribution function behavior of perfect gas and kinetic theory kinetic theory of matter

  1. $A _1 > A _2$

  2. $A _1 < A _2$

  3. A_1 = A_2$

  4. $A _1=\sqrt {A _2}$

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Correct Option: A

let A and B the two gases and given :
$\frac{{T} _{A}}{{M} _{A}}$ = 4. $\frac{{T} _{B}}{{M} _{B}}$  Where T is the temperature and M is molecular mass. If ${C} _{A}$ and  ${C} _{B}$ are the r.m.s. speed, then the ratio $\frac{{C} _{A}}{{C} _{B}}$ will be equal to:

physics kinetic theory maxwell-boltzmann speed distribution function behavior of perfect gas and kinetic theory kinetic theory of matter

  1. 2

  2. 4

  3. 1

  4. 0.5

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Correct Option: A

A mixture of ideal gases 7 kg of nitrogen and 11 Kg of $ CO _2 $ then (Take $\gamma$ for nitrogen and $CO _2$ as 1.4 and 1.3 respectively)

physics kinetic theory maxwell-boltzmann speed distribution function behavior of perfect gas and kinetic theory kinetic theory of matter

  1. Equivalent molecular weight of the mixture is 36.

  2. Equivalent molecular weight of the mixture is 18.

  3. $ \gamma $ for the mixture is 5/2

  4. $ \gamma $ for the mixture is 47/35

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Correct Option: A,D

$3$ mole of gas ''X"  and $2$ moles of gas "Y" enters from end "P" and "Q" of the cylinder respectively. The cylinder has the area of cross section , shown as
under 
The length of the cylinder is $150cm$. The gas "X" intermixes with gas "Y" at the point . If the molecular weight of the gases X and Y is $20$ and $80$ respectively, then what will be the distance of point A from Q?

physics kinetic theory maxwell-boltzmann speed distribution function behavior of perfect gas and kinetic theory kinetic theory of matter

  1. $75cm$

  2. $50cm$

  3. $37.5$

  4. $90cm$

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Correct Option: B
Explanation:

$\begin{array}{l} \frac { { rx } }{ { ry } } =\frac { { { w _{ x } } } }{ { { n _{ y } } } } \sqrt { \frac { { { M _{ y } } } }{ { { M _{ x } } } }  }  \ =\frac { 3 }{ 2 } \sqrt { \frac { { 80 } }{ { 20 } }  } =\frac { 3 }{ 1 } =3:1 \ \therefore \frac { { dis\tan  ce\, \, travelled\, \, by\, \, gas\, \, X } }{ { dis\tan  ce\, \, travelled\, \, by\, \, gas\, \, Y } } =3:1 \ \therefore dis\tan  ce\, \, of\, \, A\, \, from\, \, Q=\frac { { 150 } }{ 3 } =50\, \, cms \end{array}$

Hence, OPtion $B$ is correct.

The lowest pressure(the best Vaccum) that can be created in laboratory at 27 degree is $10^{-11} $ mm of Hg. At this pressure, the number of ideal gass molecules per $cm^{3}$ will be

physics kinetic theory maxwell-boltzmann speed distribution function behavior of perfect gas and kinetic theory kinetic theory of matter

  1. $3.22 \times 10 ^{12} $

  2. $1.61 \times 10 ^{12} $

  3. $3.21 \times 10 ^{6} $

  4. $3.22 \times 10 ^{5} $

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Correct Option: A

If $P=10^6kT$, then the number of molecules per unit volume of the gas is:

physics kinetic theory maxwell-boltzmann speed distribution function behavior of perfect gas and kinetic theory kinetic theory of matter

  1. 1

  2. $10^2$

  3. $10^3$

  4. $10^6$

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Correct Option: D