Tag: matter in our surroundings

Questions Related to matter in our surroundings

The motion of particles is _____ during freezing.

  1. Fast

  2. Moderate

  3. No motion

  4. Slow


Correct Option: D
Explanation:

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

Elastic collisions transfer:

  1. a lot of energy

  2. moderate energy between particles

  3. no energy between particles

  4. none of above


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:

  1. mixed with other molecules at low temperature.

  2. frozen into solid.

  3. condensed into liquid.

  4. melted from solid to liquid state.


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.

In which of the following conditions, the distance between the molecules of hydrogen gas would increase?

  1. increasing pressure on hydrogen contained in a closed container

  2. some hydrogen gas leaking out of the container

  3. increasing the volume of the container of hydrogen gas

  4. adding more hydrogen gas to the container without increasing the volume of the container


Correct Option: B,C
Explanation:

When hydrogen gas leaks out of the container, the molecules of the gas remaining in the container have more free space. Hence, distance between the gas molecules increases. By increasing the volume of the container also increases the distance between the molecules.

Which of the following generalizations cannot be made about the phase change of a pure substance from solid to liquid?

  1. It involves a change in potential energy.

  2. It involves no change in temperature.

  3. It involves a change in kinetic energy.

  4. It involves a change in entropy.


Correct Option: C
Explanation:

When a pure substance undergoes a phase change from solid to liquid state,there will increases in temperature so,the collision rate do not increases which implies that there is no change in kinetic energy,the entire heat involves a change in potential energy.It involves change in entropy because more free particles are generated from solid to liquid.

$\displaystyle Gas\rightarrow Solid$ 


The process is known as :

  1. sublimation

  2. condensation

  3. evaporation

  4. deposition

  5. melting


Correct Option: D
Explanation:

Deposition is a phase transition in which gas transforms into solid without passing through the liquid phase.


Hence the correct option is D.

Statement I: Water droplets form on the outside of a beaker containing an ice bath.
Statement II: Water vapor molecules in the air lose energy when they collide with the cold glass surface and condense.

  1. Both Statement I and Statement II are correct and Statement II is the correct explanation of Statement I.

  2. Both Statement I and Statement II are correct, but Statement II is not the correct explanation of Statement I. 

  3. Statement I is correct, but Statement II is incorrect.

  4. Statement I is incorrect, but Statement II is correct.


Correct Option: A
Explanation:

Condensation is a process in which gaseous molecules lose energy and gets converted to liquid state.

Water droplets are formed on outside of a beaker containing ice bath because water molecules in air loose energy when they collide with the cold glass surface  and condense.

An electron having mass '$m$' and kinetic energy $E$ enter in the uniform magnetic field $B$ perpendicularly, then its frequency will be:

  1. $\displaystyle \dfrac{eE}{qVB}$

  2. $\displaystyle \dfrac{2\pi m}{eB}$

  3. $\displaystyle \dfrac{eB}{2\pi m}$

  4. $\displaystyle \dfrac{2m}{eBE}$


Correct Option: C
Explanation:

It velocity of particle is perpendicular to the magnetic field,the particles moves in a circle.The centripetal force is experienced by electron is $qVB$

$\cfrac { { m }v^{ 2 } }{ r } =qVB\ \cfrac { mv }{ r } =qB\ $
$mw=qB$
$w=qB/m$
$f=\cfrac { qB }{ 2\pi m } $
Frequency$=\cfrac { eB }{ 2\pi m } $

A proton is about 1840 times heavier than an electron. When it is accelerated by a potential difference of 1 kV, its kinetic energy will be :

  1. 1840 keV

  2. 1/1840 keV

  3. 1 keV

  4. 920 keV


Correct Option: C
Explanation:
We know that :

Kinetic energy = Relative charge$\times$ accelerating potential

$KE=1e\times 1kV$

$KE=1keV$

Hence the correct option is C.

As the water heats up from 280 K to 310 K, the average kinetic energy of its molecules will:

  1. increase

  2. decrease

  3. stay the same

  4. increase, then decrease

  5. decrease, then increase


Correct Option: A
Explanation:

$T$ $\alpha$  $KE$
Higher the temperature higher will be kinetic energy .
Hence, as the water heats up from 280 K to 310 K, the average kinetic energy of the its molecules will increase.