Science M.C.Q. [1 M]

Have a friend put their hands on your shoulder and push down. Now try to jump upwards.
It's difficult to do so right?
You would need more energy to jump higher correct?
The same applies to molecules of water.
The air pressure exerts a force on them which they must overcome in order to boil.
The greater the air pressure the greater the temperature at which the water will boil.

The particles of salt get into the spaces between particles of water

The force of attraction between particles of gas is negligible. Because of this, particles of gas move in all directions. Thus, a gas fills the vessel completely in which it is kept.

Sublimation

Particles of matter are continuously moving from one end to another, thereby transferring smell from one place to another.The reason why the smell of hot sizzling food goes farther than cold food is because the kinetic energy of the particles of matter increases with the increase in temperature.
So, particles in the smell of hot food have a higher kinetic energy and hence, move farther than those of cold food.

Sublimation is the change of solid/ gas phase directly from the solid/ gas phase to the gaseous/ solid phase without passing through the intermediate liquid phase.

An earthen pot has a large number of extremely small pores on its wall. Some of the water continuously keeps seeping through these pores. This water evaporates continuously and takes the latent heat required for vaporization from the earthen pot and the remaining water. In this way, the remaining water loses heat and gets cooled.

Boiling is a bulk phenomenon because all molecules gain energy on heating.Evaporation is a surface phenomenon as the molecules of the surface gets sufficient energy to overcome the force of attraction which will help in converting to the vapour phase.
Dilution is also a bulk phenomenon as the volume of solution increases throughout the bulk of the solution.

Some hydrogen gas leaking out of the container will result in the availability of more free space for the remaining hydrogen molecules. Hence, the particles will be able to move more freely and the distance between them will increase. Increasing the volume of the container of hydrogen gas will also result in the increase of motion of particles. There will be more space available for the particles to move. As a result, the particles will move away from each other causing an increase in distance between them.

On the increasing temperature, the energy of particles increases, therefore, it is easy to convert to vapor phase as compared to particles that have less or no energy.

Most impurities have boiling points lower than that of water.
During evaporation, only water evaporates leaving the impurities behind.
So, when we condense the water vapour, we mostly get pure water with no impurities in it.

During evaporation, water does not convert into a gas or steam, but the random movement of molecules on the surface of the water provides some of the molecules with enough energy to escape from the surface into the air.

The force of attraction between the particles increases as we go from liquid to gas so the required order is: Oxygen

Evaporation is a type of vaporization of a liquid that occurs from the surface of a liquid into a gaseous phase below its boiling point.

Both water and potassium permanganate are made up of tiny particles. The particles of potassium permanganate are coloured while those of water are colorless. When the crystals of potassium permanganate are kept in water, the purple-coloured crystals of potassium permanganate break further into smaller particles that occupy the space between the molecules of water imparting a purple colour to the water.

The transformation of a solid directly into vapour, on heating, is known as sublimation.

With the help of experiments it can be shown that at low temperature and high pressures, gases will liquefy. Because these factors affect the interaction force of molecules i.e. the molecules are able to establish a force of attraction between them on lowering the temperature and increasing pressure.

The rates of evaporation, diffusion and expansion of gases increases due to increase in temperature because when temperature increases the kinetic energy of molecules increases, which breaks or weakens the interaction between the atoms and sets the molecules free.

This value is fixed and is found by performing the experiment in the lab.

An earthenware keeps water cool but a metallic vessel does not because earthenware has pores.
Because of these pores, some of the water can easily evaporate through them, because of this evaporation the water inside is kept cool.
This is not possible in a metallic vessel.

Latent heat is absorbed because during change of state because it is the heat energy that has to be supplied to change the state of a substance.

This experiment proves that matter is made up of tiny particles which spread through the solution making it coloured.

Dissolution of sugar into water

Lnter-particle spaces are minimum in solids, due to which solids are generally densely packed.
Liquids have more inter-particle spaces than solids and gases have the maximum inter-particle spaces between them.

Electrically conductive

Air, earth, sky, fire, water

Matter changes from one state to another by changing temperature or pressure.
We can convert matter from one state to another by adding or removing energy(heat), i.e, by changing temperature.
Or by changing the pressure we can bring the molecules closer or take them far apart.
This also can change the state of the matter.

Evaporation, diffusion and expansion of gases increase on raising the temperature.Evaporation rate increases because on increasing temperature, kinetic energy of molecules increases, so the molecules present at the surface of the liquid leave the surface quickly and go into the vapour state. Diffusion and expansion of gases also increase as the molecules move more rapidly and try to occupy more space.

2

Latent heat is the energy released or absorbed by a body during a constant temperature process.
An example is a phase transition such as ice melting or water boiling.
Heat absorbed during melting is called latent heat fusion.

Liquid requires latent heat of vaporization.
So, when the liquid takes up the heat from the surrounding to vaporize, the temperature of surrounding reduces, and it cools down due to loss of heat.

Particles of matter are continuously moving

Solid-state has the least intermolecular space and most packed structure.
On heating of a solid, the intermolecular forces decrease, space between the molecules increases.
The particles gain energy and there is an increase in kinetic energy and the molecules move faster.

When the temperature of a substance is increased collision, rate between particles increases which increases.
The speed of particles which implies that the kinetic energy of particles is directly proportional to the temperature of the substance.

Spacing between particles of gas can be can be decreased by increasing pressure.
Hence, gases have high compressibility. Solids and liquids are not compressible as the spacing between their particles cannot be decreased.

Spirits are very volatile liquids, which means they evaporate very quickly. When we apply spirit on our body, its particles gain energy from the surface and evaporate, thus, giving our body a cool sensation.

The water kept in an earthen pot remains cool even in summer because of evaporation.
Earthen pot has a large number of tiny pores in its walls and some of the water molecules continuously keep seeping through these pores to outside the pot.
This water evaporates continuously and takes the latent heat required for vaporization from the remaining water. In this way, the remaining water loses heat and gets cooled.

Explanation: (B) Sodium chloride.
Sodium chloride does not undergo sublimation because it does not show direct change from solid state to liquid state.

Explanation:(A) Increase in temperature of water
As the temperature of the water increases, the kinetic energy increases
As a result, the force of attraction between the molecules decreases, and the molecules become more and more separated.
Thus, increasing the temperature of a body of water also often increases evaporation.
This is because as the temperature rises, the water molecules begin moving about more rapidly and will finally escape.

Temperature: The rate of evaporation increases with an increase in temperature.
Surface area: The rate of evaporation increases with an increase in surface area.
Humidity: The amount of water vapour present in the air is called humidity. The rate of evaporation decreases with an increase in humidity.
Wind speed: Evaporation increases with an increase in wind speed.

All

Deposition is the phase transition in which gas transforms into solid without passing through the liquid phase. Deposition is a thermodynamic process. The reverse of deposition is sublimation and hence sometimes deposition is called desublimation.