Matter in our surrounding Worksheet-4

Matter in our surrounding Worksheet-4

The smell of hot sizzling food reaches us several metres away. However, it is not so in case the food is cold. Explain.

A. kinetic energy of the particles released by hot food is very high in the vapour state

B. kinetic energy of the particles released by cold food is very high in the vapour state

C. Vapours are not released by cold food where as vapours are released by hot food

A diver is able to cut through water in a swimming pool. Which property of matter does this observation show?

A. There is very less force of attraction between the particles of water

B. Particles of water are scattered as there is large intermolecular space between them

C. Interparticle space is present in water helps the diver to cut through water

D. Water exists in all the three states of matter

The mass per unit volume of a substance is known as density (density=mass/volume). Arrange the following in order of increasing density:

Air, exhaust from chimneys, honey, water, chalk, cotton and iron.

A. Cotton, honey, exhaust from chimneys, chalk, iron, air

B. Air, exhaust from chimneys, cotton, water, honey, chalk, iron

C. honey, chalk, iron, air, exhaust from chimneys, cotton

D. Air, chalk, iron,exhaust from chimneys, cotton, water, honey

A gas exerts pressure on the walls of the container because _____.

A. Particles of gases are in random motion

B. Particles of gas strike the walls of container with certain force

C. Weak intermolecular force of attraction between the molecules of gas

D. Large intermolecular spaces

Why should we call a wooden table a solid?

A. It is very hard and rigid.

B. It shape cannot be changed by altering temperature or pressure.

C. It is quite heavy which means its density is high.

D. All of these

We can easily move our hand in air but to do so the same through a solid block of wood, we need a ‘Karate expert’ because______

A. In air interparticle space is less and also there is weak intermolecular force of attraction

B. In air particles are in constant motion

C. Collision between the particles of air helps a person to move hand in air

D. In air Interparticle space is large and also there is weak intermolecular force of attraction

Though liquids generally have low density as compared to solids, yet ice floats in water.

A. Ice has a cage like structure with vacant spaces making it less dense as compared to water

B. The number of particles in ice are less than in water

C. Ice absorbs heat from the surrounding and melts. This process makes ice float on water

D. All of these

What is the physical state of water at : (a) 250ºC (b) 100ºC?

A. (a) Both vapour and liquid (b) only vapour

B. (a) only vapour (b) Both vapour and liquid

C. (a) vapour (b) vapour

For any substance, why does the temperature remain constant during the change of state even when the heat is supplied?

A. Heat supplied during the change of state is used to increase kinetic energy of particles hence temperature remain constant

B. Heat supplied during change of state is absorbed as latent heat hence the temperature remains constant

C. Once the boiling point is reached temperature remains constant as water and vapour exist in equilibrium

D. Can’t say

Atmospheric gases be liquefied by _______.

A. Increasing pressure and decreasing temperature

B. Decreasing pressure and decreasing temperature

C. Decreasing pressure and increasing temperature

D. Decreasing voulme

A cooler is quite effective on a hot and dry day because ______.

A. During evaporation water absorbs energy from the surroundings thus causing the cooling

B. During hot and sunny day wind blows faster thus causing cooling

C. Cooler causes the same cooling in any season

D. Rate of evaporation of water circulating in cooler is more in hot and sunny day

When we pour some acetone or perfume on our palm, we get a cooling sensation because ______.

A. Acetone or perfume condense on the palm thus causing cooling

B. The temperature of acetone or perfume is very less thus we feel cold

C. Acetone or perfume evaporates on palm thus causing cooling effect

D. The gas present in perfume causes cooling effect

Why can we sip hot tea from a saucer faster than from a cup ?

A. Evaporation in saucer is more as compared to cup

B. Evaporation of liquid is depends upon the surface area, temperature and humidity

C. A saucer has more surface area which increases the rate of evaporation thus causing the cooling of liquid

D. More is the evaporation more is the cooling caused

E. All of these

Why naphthalene balls disappear with time without leaving any solid?

We can get the smell of perfume sitting several metres away.

A. Naphthalene evaporates B. Naphthalene condenses

C. Naphthalene melts D. Naphthalene sublimes

Arrange the following substances in increasing order of force of attraction between the particles: water, sugar, oxygen.

A. Sugar > Oxygen < water B. Sugar < Oxygen < water

C. Oxygen< water < sugar D. Water < Oxygen <sugar

What is the physical state of water at

(a)25°C (b)0°C (c)100°C?

A. (a) liquid (b) solid and liquid (c) liquid and gas

B. (a) liquid and vapour (b) solid and liquid (c) liquid and gas

C. (a) liquid (b) solid (c) gas and liquid

D. (a) liquid (b) liquid (c) gas

Ice at 273 K causes more cooling than water at the same temperature because ______

A. Ice evaporates taking up energy from the surroundings thus causing cooling

B. Water freezes at 273 k giving out heat to the surroundings

C. Ice condenses absorbing latent heat from the surroundings thus causing cooling

D. Ice melts taking up energy from the surroundings thus causing cooling

Answer Key:

Explanation: When food is sizzling hot, it releases the vapours of its contents. Since the kinetic energy of the particles is very high in the vapour state, they can reach us even at a distance of several metres However, when the food is cold, the vapours released will be comparatively less. Moreover, their kinetic energy will be also very small. Under these conditions, one has to come quite close in order to smell the contents of the food.

Explanation: This shows that in water which represents the liquid state of matter, there are sufficient inter particle spaces. That is why, a diver is able to cut through water. He might not do the same had these spaces been very small (e.g. in solid state).

Explanation: The increasing order of density for the given substances is:

Air, exhaust from chimneys, cotton, water, honey, chalk, iron.

Actually, the density of a substance depends upon the number of particles per unit volume as per their mass. The number of the particles is related to their size as well as the attractive forces among them.

Explanation: The molecules in a gas have large kinetic energy. They strike the walls of the container with certain force and impart momentum to them. The force per unit area or momentum is responsible for the pressure of the gas.

Explanation: A wooden table should be called a solid because it has characteristics of the solid state. Example,

(i) It is very hard and rigid.

(ii) It shape cannot be changed by altering temperature or pressure.

(iii)It is quite heavy which means high density.

(iv)There is no movement of the constituent particles present.

Explanation: In air the interparticle spaces are very large and the interparticle forces of attraction are quite weak. These spaces help in moving our hand in air, But in a solid block, the constituent particles are quite close and the interparticle forces are very strong. In case, one has to move his hand through a solid, it will be extremely difficult. Only a karate expert may do so.

Explanation: Ice (solid state) is expected to be heavier than water(liquid state).But it is lighter and floats over water. Actually, ice has a cage like structure, which means that there are vacant spaces in ice. The vacant spaces are comparatively less in water. Therefore, water is dense as compared to ice or ice floats over water.

Explanation: Boiling point temperature of water is 100ºC. Above this temperature (250º), water exists in the gaseous state i.e., as vapour or as steam. However, at 100ºC, both liquid and gaseous states are present. Actually, at the boiling point liquid and gaseous state of a substance exist in equilibrium. We may conclude that at 100ºC, both liquid water and vapours are present but at 250ºC we have only vapours or steam and no liquid.

Explanation: Once the change of state of a substance begins or starts, the energy supplied is being used up as latent heat. It means that it does not increase the kinetic energy of the particles and is used up only to bring about a change in state. Therefore, the temperature becomes constant.

Explanation: The atomospheric gases can be liquified by increasing pressure and decreasing temperature.

Explanation: Under the conditions, the humidity level in the atmosphere is quite low and the rate of evaporation of water is high. Since cooling is caused during evaporation, a cooler is quite effective on a hot and dry day.

Explanation: Both acetone and perfume are low boiling liquids. When any of them is poured on the palm, it readily changes into vapours or evaporates. For this, it needs some energy which is taken from the palm. Temperature of the palm gets lowered and we get a cooling sensation.

Explanation: Naphthalene has a tendency to sublime i.e. it changes directly to the gaseous state. Therefore, the size of the naphthalene balls slowly decreases and ultimately they disappear. No solid residue is left.

Explanation: The three substances differ in their physical state at normal temperature. Oxygen is a gas, water a liquid while sugar is a crystalline solid. Keeping this is mind, the increasing order of attraction between the particles is : oxygen< water<sugar.

Explanation: (a) At 25°C, water is in the liquid state (b) At 0°C, Water can exist both in the solid state (ice) and in liquid state. This Temperature represents the melting point of ice and freezing point of water

(c) At 100°C, water is present both in the liquid and vapour states. This temperature corresponds to the boiling point of water and liquefaction temperature of steam.

Explanation: When ice (solid state) is to melt at 273 K, it takes up certain energy from the surroundings to overcome the attractive forces between the solid particles. As a result, the temperature of the surroundings lowers causing cooling. However, water is already in the liquid state and has no tendency to change to the vapour state at this temperature. It will hardly take up any energy from the surroundings. Therefore, it will cause comparatively less cooling.