Tag: diffusion in different states of matter

Questions Related to diffusion in different states of matter

The translational kinetic energy of N molecules of $O _2$ is x J at $-123^o$C. Another sample of $O _2$ at $27^o$C has translational kinetic energy of $2x$ J. The latter sample contains:

chemistry matter in our surroundings diffusion in different states of matter properties of solids, liquid, and gas particle theory of matter

  1. N molecules of $O _2$

  2. $2N$ molecules of $O _2$

  3. $N/2$ molecules of $O _2$

  4. $N/4$ molecules of $O _2$

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Correct Option: A
Explanation:

$T _1=-123^o$ K $=150$ K, $T _2=27^oC=300$ K


$KE _1=xJ$

$KE _2=2xJ$

Average translational kinetic energy:

$E=\dfrac{3}{2}nRT$

$=\dfrac{3}{2}\dfrac{N}{N _A}RT$

$\dfrac {x}{2x} = \dfrac{\dfrac{3NRT _1}{2N _A}}{\dfrac{3N _1RT _2}{2N _A}}$

$\dfrac{1}{2}=\dfrac{N}{N _1}\times \dfrac{150}{300}$

$N=N _1$

Hence, the correct answer is option $A$.

The helium atom is two times heavier than a hydrogen molecule. At $298$ K, the average kinetic energy of a helium atom is:

chemistry matter in our surroundings diffusion in different states of matter properties of solids, liquid, and gas particle theory of matter

  1. Two times that of hydrogen molecule

  2. Same as that of a hydrogen molecules

  3. Four times that of a hydrogen molecules

  4. Half that of a hydrogen molecule

Show answer
Correct Option: B
Explanation:

Using the formula of average kinetic energy:


$K.E. = \dfrac 32 KT$

K.E does not depend upon mass.


$\therefore$ At the same temperature, K.E will be same.

Hence, option $B$ is correct.

Consider three identical flasks with different gases:


Flask A: CO at $760$ torr and $273$ K
Flask B: $N _2$ at $250$ torr and $273$ K
Flask C: $H _2$ at $100$ torr and $273$ K

In which flask will the molecules have the greatest average kinetic energy per mole?

chemistry matter in our surroundings diffusion in different states of matter properties of solids, liquid, and gas particle theory of matter

  1. A

  2. B

  3. C

  4. Same in all

Show answer
Correct Option: D
Explanation:

Avg kinetic energy$=\dfrac{3}{2}nRT$


$\therefore$ For $1$ mole:-$\dfrac{3}{2}RT$

As the temperature in all of these is same.

$\therefore$ Avg kinetic energy of all these are equal.

Hence, option $D$ is correct.

At what temperature will the total translational kinetic energy of $0.30$ mole of He gas be the same as the total translational kinetic energy of $0.40$ mol of Ar at $400$ K?

chemistry matter in our surroundings diffusion in different states of matter properties of solids, liquid, and gas particle theory of matter

  1. $533$ K

  2. $400$ K

  3. $300$ K

  4. $266$ K

Show answer
Correct Option: A
Explanation:

$n _1=0.30$ mol, $T _1=?$


$n _2=0.40$ mol, $T _2=400$ K

Using $n _1T _1=n _2T _2$

$0.3\times T _1=0.4\times T _2$

$T _1=\dfrac{4}{3}\times 400$

$=533$ K

Hence, option $A$ is correct.

Steam at ${100^0 C}$ causes more severe burns than the water at the same temperature because:

chemistry matter in our surroundings diffusion in different states of matter properties of solids, liquid, and gas particle theory of matter

  1. Steam is a gas

  2. Steam is highly combustible

  3. Steam can provide more heat

  4. Steam cannot do more work

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Correct Option: C
Explanation:

In addiiton to the temperatre steam has latent heat of vapourization which it acquires after converting into steam from water.

A solid consists of low kinetic energy, vibrating particles locked into position by interparticle attractive forces. When heat is applied, energy is absorbed and the particles start vibrating more vigorously.

chemistry matter in our surroundings diffusion in different states of matter properties of solids, liquid, and gas particle theory of matter

  1. True

  2. False

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Correct Option: A
Explanation:

A solid consists of low kinetic energy vibrating particles locked into position by interparticle attractive forces. When heat is applied, energy is absorbed and the particles start vibrating more vigorously.
Finally, the vibrations become energetic enough to overcome the attractive forces, and the particles start sliding out of their positions to flow about. The solid is now melting into a liquid.

Why does evaporating sweat cools human body?

chemistry matter in our surroundings diffusion in different states of matter properties of solids, liquid, and gas particle theory of matter

  1. Condensation

  2. Evaporate cooling

  3. Evaporate heating

  4. Melting

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Correct Option: B
Explanation:

Evaporation involves conversion of liquid to vapor which happens when latent heat is absorbed by the liquid.

During sweating, human body is cooled by evaporation of sweat molecules which takes place by absorbing latent heat of evaporation from our body.

The motion of particles is _____ during freezing.

chemistry matter in our surroundings diffusion in different states of matter properties of solids, liquid, and gas particle theory of matter

  1. Fast

  2. Moderate

  3. No motion

  4. Slow

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Correct Option: D
Explanation:

During freezing, inter-molecular attraction increases and the motion of particles becomes slow.

Elastic collisions transfer:

chemistry matter in our surroundings diffusion in different states of matter properties of solids, liquid, and gas particle theory of matter

  1. a lot of energy

  2. moderate energy between particles

  3. no energy between particles

  4. none of above

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Correct Option: C
Explanation:

All collisions between the particles of matter are perfectly elastic. Elastic collisions transfer no energy between particles. Each particle has exactly the same energy after the collision as before.

According to kinetic theory of gases, molecular kinetic energy increases when:

chemistry matter in our surroundings diffusion in different states of matter properties of solids, liquid, and gas particle theory of matter

  1. mixed with other molecules at low temperature.

  2. frozen into solid.

  3. condensed into liquid.

  4. melted from solid to liquid state.

Show answer
Correct Option: D
Explanation:

Molecular kinetic energy is maximum in gases and least in solids. Hence, a substance is melted from solid to liquid state, its kinetic energy increases.