Tag: matter in our surroundings

Questions Related to matter in our surroundings

Solid $\rightarrow$ Gas  conversion is known as:

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

  1. sublimation

  2. condensation

  3. evaporation

  4. deposition

  5. melting

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Correct Option: A
Explanation:

Option A is the correct answer.

Sublimation is the process of conversion of solid particles into gas particles.

Matter undergoes a change. The changes are of two types : Physical and chemical change. A physical change is a change that involves only a change in the physical state of matter.
Its chemical properties remain the same. Usually increasing the temperature of applying pressure or both brings about a physical change. On reversing the condition, i.e., reducing the temperature or reducing the pressure or both, the original state of matter is restored. In other words, physical changes are reversible. A chemical change is a change that involves a change in the chemical composition of matter. A new substance is formed. In a chemical change, the chemical and physical properties of the substance is formed. In a chemical change, the chemical and physical properties of the substance formed will be different from the original substance. When zinc carbonate is heated and cooled, the change(s) that are observed are :

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

  1. Physical

  2. Nuclear changes

  3. First chemical and then physical

  4. First physical and then chemical

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Correct Option: C
Explanation:

First zinc carbonate decomposes to give zinc oxide and $CO _2$ and zinc oxide appears yellow when hot and white when cold. Initially, zinc carbonate under goes chemical change. Cooling of zinc oxide a goes physical change, to change its colour from yellow to white.

The translational kinetic energy of $10^{20}$ molecules of nitrogen at a certain temperature is $0.63$ J. The temperature is:

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

  1. $23^o$ C

  2. $31.3^o$ C

  3. $30.1^o$ C

  4. $43.3^o$ C

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Correct Option: B
Explanation:

$K.E=\dfrac{3}{2}N K _BT$


$N=10^{20}, K _B=1.38\times 10^{-23}$ Joule/, KE$=0.63$ J

$0.63=\dfrac{3}{2}\times 10\times 1.38\times 10^{-23}\times T$

$\Rightarrow T=\dfrac{0.63\times 2}{1.383}\times 10^3$

     $T=304.3$K

     $T=31.3^o$ C.

Hence, option $B$ is correct.

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 $O _2$

Show answer
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

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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

Show answer
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.