Term
Give reasons for the following observation on: The smell of hot sizzling food reaches
you several metres away, but to get the smell from cold food you have to go close. |
|
Definition
The reason behind this is DIffusion.
The particles of hot food have more temperature & more ki neti c energy and hence
the rate of di f f usi on is more than the particles of cold food.
The smell of hot sizzling food reaches several meters away. |
|
|
Term
A di ver i s abl e to cut through water i n a swi mmi ng pool . Whi ch property of matter
does thi s observati on show? |
|
Definition
The reason behind this is less intermolecular force and more intermolecular space
in Water particles.
Because of the above driver is able to overcome water force and cut through it. |
|
|
Term
| What are the characteristics of the particles of matter? |
|
Definition
The characteristics of the particles of matter are:
(1) Particl es have i ntermol ecul ar space.
(2) Particl es have i ntermol ecul ar f orce.
(3) Particles of matter are moving continuously |
|
|
Term
| What is/comment: Density? |
|
Definition
The mass per unit volume of a substance is called density.
Density = mass/volume.
Units =gm/ml |
|
|
Term
|
Definition
Rigidity:
The tendency of a substance to retain/maintain its shape when subjected to
outside force. |
|
|
Term
|
Definition
Compressi bi l i ty : T he matter has i ntermol ecul ar space. The external force applied
on the matter can bring these particles closer. T This property is cal l ed
compressibility. Gases and liquids are compressible. |
|
|
Term
|
Definition
Fluidity:
The tendency of particles to flow is called
fluidity.
Liquids and gases flow. |
|
|
Term
Arrange the following order of
increasing density –
air, exhaust from chimneys,
honey, water, chalk, cotton and iron |
|
Definition
increasing density:
ai r < exhaust f rom chimneys < cotton < water < honey < chal k < i ron. |
|
|
Term
Comment on
Filling of a gas container |
|
Definition
Filling of a gas container:
Gases have particles which vibrate randomly in all directions. The gas can fill
the container. |
|
|
Term
Comment on: S h a pe,
K i ne t i c e ne rg y,
D e ns i t y. |
|
Definition
Shape : Solids have maxi mum intermolecular force and definite shape.Whereas
liquids and gases take the shape of a container.
Kinetic e ne rg y: The energy possessed by particles due to their motion is
cal l ed ki neti c energy. Molecules of gases vibrate randomly as they have maximum
ki neti c energy.
Density: It is defined as mass per unit volume, the
solids have highest density. |
|
|
Term
Gi ve reasons :
**A gas f i l l s compl etel y the vessel i n whi ch i t i s kept.
**A gas exerts pressure on the wal l s of the contai ner. |
|
Definition
A gas fill s completely the vessel in which it is kept
The molecules of gas have high ki neti c energy due to which they keep moving in
all di recti ons and hence fill the vessel completely in which they are kept.
A gas exerts pressure on the walls of the container.
A gas exerts pressure on the walls of the container because the molecules of the
gas are in constant random motion due to high kinetic energy. These molecules
constantly vibrate, move, and hit the walls of the container ner thereby exerting
pressure on it.
D uri |
|
|
Term
Reason:
A wooden table should be called a solid. |
|
Definition
The molecules/particles of wooden table are tightly packed
with each other,
As,there is no intermolecular space, it cannot be compressed, it cannot flow, all thesecharacteristics are of solid. So a wooden table should becalled a solid. |
|
|
Term
We can easily move our hand in air but to do the same through a solid block of
wood we need a karate expert.Expain |
|
Definition
Particles in air have less intermolecular force and more space between them when compared to solid particles.
Hence we require a lot of energy to move hand through a solid block than air. |
|
|
Term
Liquids generally have lower density as compared to solids. But you must have
observed that ice floats on water. Find out why |
|
Definition
Ice is a solid but its density is lower than water due to its structure. The
molecules in ice make a cage - like structure
with a lot of vacant
spaces, this makes ice float on water. |
|
|
Term
For any substance, why does the temperature remain constant during the change of
state |
|
Definition
During the change of state of any matter heat is supplied to the substance. The
molecules of this matter use heat to overcome the force of attraction between the
particles, at this period of time, temperature remains constant. This extra heat is
acquired by the molecules in the form of hidden heat called
latent heat to change from one state of matter to the other state |
|
|
Term
What is the physical state of water at:
(a) 250°C
(b) 100°C |
|
Definition
a) 250°C = gas
(b) 100°C l i qui d as wel l as gas |
|
|
Term
| Suggest a method to liquefy atmospheric gases. |
|
Definition
[image]
The atmospheric gases are taken in a
cylinder with a piston fitted on it. By
cooling and applying pressure on them, the
gases can be liquefied. |
|
|
Term
| Why does a desert cool er cool better on a hot dry day? |
|
Definition
The outer walls of the cooler get sprinkled by water constantly. This water evaporates due to hot dry weather.
This evaporation causes cooling of the inside air of
the cooler. This cool air is sent into the room by the fan. |
|
|
Term
| How does the water kept in an earthen pot (matka) become cool during summer? |
|
Definition
The earthen pot is porous with a lot of pores on it.
The water oozes out through
these pores and the water gets evaporated at the surface of the pot thereby causing a cooling effect. This makes the pot cold and the water inside the pot cools by this process. |
|
|
Term
| Why does our palm feel cold when we put some acetone or petrol or perfume on it? |
|
Definition
Acetone, petrol, or perfume are very volatile and evaporate when they come into contact with the body taking its temperature.
This evaporation causes a cooling sensation on our hands as the temperature has come down. |
|
|
Term
Why are we able to sip hot tea or milk faster
from a saucer rather than a cup?/ |
|
Definition
Tea in a saucer has a larger surface area than in a cup.
The rate of evaporation is directly proportional to
surface area.Hence,The cooling of
tea in a saucer takes place sooner than in a cup. Hence we are able to sip hot tea or milk faster from a saucer rather than a cup. |
|
|
Term
| What type of clothes should we wear in summer? |
|
Definition
We should wear light coloured cotton clothes in summer.
Light color because it reflects heat.
Cotton clothes because it has pores in it, which absorb sweat and allow the sweat to evaporate faster thereby giving a cooling effect. |
|
|
Term
Gi ve reason f or the f ol l owi ng observati ons.
(a) Naphthalene balls disappear with time without leaving any solid.
(b) We can get the smell of perfume sitting several meters away. |
|
Definition
a) Naphthalene balls disappear within no time without
leaving any solid, because naphthalene balls sublime and directly change into vapour state without leaving any solid.
(b) We can get the smell of perfume sitting several metres away because perfume
contain volatile solvent and diffuse faster and can reach people sitting several metres away |
|
|
Term
Arrange the following substances in
increasing order of forces of attraction
between the particles—
water, sugar, oxygen |
|
Definition
| Oxygen —> water —> sugar. |
|
|
Term
What is the physical state of water at—
(a) 25°C
(bj 0°C
(cj 100°C |
|
Definition
a) 25°C i s l i qui d
(b) 0°C i s sol i d or l i qui d
(c) 100°C i s l i qui d and gas |
|
|
Term
Give two reasons to j usti f y
(a) water at room temperature is a liquid.
(b) an iron almirah is a solid at room temperature. |
|
Definition
(a) Water at room temperature is a liquid because its freezing point is 0°C and boiling point is 100°C.
(b) An iron almirah is solid at room temperature because
the melting point of iron is
higher than room temperature |
|
|
Term
| Why is ice at 273K more effective in cooling than water at the same temperature |
|
Definition
I ce at 273 K wi l l absorb heat energy or latent heat from the medium to overcome
the f usi on to become water. Hence the cooling effect of ice is more than the
water at the same temperature because water does not absorb this extra heat from the medium |
|
|
Term
| What produces more severe bums, boiling water or steam? |
|
Definition
Steam at 100°C will produce more severe bums as extra heat
is hidden in it called latent heat, whereas boiling water does not have this hidden heat. |
|
|
Term
[image]
Name A, B, C, D , E and F in the following
diagram showing change in its state. |
|
Definition
A —> Li quef i cati on/mel ti ng/f usi on
B —> Vapori sati on/evaporati on
C—>Condensati on
D—> Sol i di f i cati on
E —> Subl i mati on
F —> Subl i mati on |
|
|
Term
[image]
The diagram below represents the change
in state of matter, Name the phenomenon
represented as L, M, N , O, P, Q |
|
Definition
|
|
Term
Look at the following experimental set-up while dilution of purple colored
KMnO4 solution into
From this, it can be concluded that
I . particles of matter are in a state of continuous motion
I I . Particles of matter have some spaces of continuous motion
I I I . Particles of matter are very tiny
The correct statements are
a) I and I I b) I I and I I I c) only I I
d) only I I I |
|
Definition
|
|
Term
Give reason for the following questions:
Solid Carbondioxide is stored under high pressure/
(What is dry ice? why it is stored under high pressure?) |
|
Definition
solid carbon dioxide is known as dry ice. Solid carbondioxide is stored under
high pressure because, on decreasing the pressure solid carbon dioxide gets
converted directly into carbon dioxide gas due to sublimation. |
|
|
Term
At many places, especially in villages, people of ten sprinkle water on the ground in
front of their homes during the hot summer evening. |
|
Definition
| people sprinkle water on the ground in front of their houses because the water on the ground evaporates taking the latent heat from the atmosphere and thus producing a cooling effect. |
|
|
Term
| The rate of diffusi on is much faster in liquids than in solids |
|
Definition
In the liquid state, particles have greater space and weaker force of attraction
between them as compared to particles in solid-state. Thus, in liquids, the particles move freely as compared to solids. Hence it has a higher rate of di f f usi on. |
|
|
Term
| It is not proper to regard the gaseous state of ammonia as vapours. expl ai n |
|
Definition
| ammonia remains in the gaseous state at room temperature, so it's called a gas. We call something a vapour when that element remains a solid or a liqui d at room temperature but vaporizes at a temp. |
|
|
Term
Asserti on: Sublimation is the change of gaseous state directly to solid state
without going through liquid state
Reason: The state of matter can be changed by changing temperature or pressure |
|
Definition
Asserti on and Reason:
a) Both asserti on and reason are correct, and the reason i s the correct expl anati on
f or asserti on.
b) Both asserti on and reason are correct, but reason i s not the correct expl anati on
f or asserti on.
c) Asserti on i s true but reason i s f al se.
d) Both asserti on and reason are f al se. |
|
|
Term
Asserti on: Physi cal state of water at 25°C i s Li qui d
Reason: physical state of
water at 0°C is liqui d or solid |
|
Definition
Asserti on and Reason:
a) Both asserti on and reason are correct, and the reason i s the correct expl anati on
f or asserti on.
b) Both asserti on and reason are correct, but reason i s not the correct expl anati on
f or asserti on.
c) Asserti on i s true but reason i s f al se.
d) Both asserti on and reason are f al se. |
|
|
Term
Asserti on: Evaporati on causes cool i ng ef f ect
Reason: T he rate of evaporati on
depends upon the surf ace area exposed to the atmosphere |
|
Definition
Asserti on and Reason:
a) Both asserti on and reason are correct, and the reason i s the correct expl anati on
f or asserti on.
b) Both asserti on and reason are correct, but reason i s not the correct expl anati on
f or asserti on.
c) Asserti on i s true but reason i s f al se.
d) Both asserti on and reason are f al se. |
|
|
Term
Asserti on: Diffusion is the process by which different substances mix as a result of
the random motion of their molecules
Reason: The arrangement of particles is most
ordered in the case of solids |
|
Definition
Asserti on and Reason:
a) Both asserti on and reason are correct, and the reason i s the correct expl anati on
f or asserti on.
b) Both asserti on and reason are correct, but reason i s not the correct expl anati on
f or asserti on.
c) Asserti on i s true but reason i s f al se.
d) Both asserti on and reason are f al se. |
|
|
Term
Asserti on: The temperature above which a gas cannot be liquified is called
critical temperature
Reason: The volume occupied by a gas at
critical temperature and pressure is called critical volume. |
|
Definition
Asserti on and Reason:
a) Both asserti on and reason are correct, and the reason i s the correct expl anati on
f or asserti on.
b) Both asserti on and reason are correct, but reason i s not the correct expl anati on
f or asserti on.
c) Asserti on i s true but reason i s f al se.
d) Both asserti on and reason are f al se. |
|
|
Term
| Explain how gases can be liquified. |
|
Definition
| A gases can be l i qui f i ed by i ncreasi ng pressure and reduci ng the temperature |
|
|
Term
Bose Einstein condensate have:
Very low kinetic energy
Low kinetic energy
High kinetic energy
Highest kineti c energy |
|
Definition
The condensate f function on is created when the temperature
lowers to a point where
the item's kinetic energy is considerably less than its potential energy.As a result,the right answer is Low Kinetic
Energy. |
|
|
Term
In which of the following conditions, the distance between the molecules of
hydrogen gas would increase
(i ) Increasing pressure on hydrogen contained in a closed container
(i i ) Some hydrogen gas leaked out of the container
(i i i ) increasing the volume of the container of hydrogen gas
(i v) Adding more hydrogen gas to the container without increasing the volume of
the container
(a) (i ) and (i i i ) (b) (i ) and(i v) (c) (i i ) and (i i i ) (d) (i i ) and (i v) |
|
Definition
(c) (i i ) and (i i i )
(i i ) Some hydrogen gas leaking out of the container would accommodate more
space so the distance between the molecules of hydrogen gas would increase,
thus it is the correct answer.
(i i i )Increasing the volume of the container of hydrogen gas will impart more space to the hydrogen gas and bond distance may increase. |
|
|
Term
Asserti on:-When sugar is poured i n water, the taste of water becomes sweet.
Reason-sugar completely dissolved in water with giving its own character |
|
Definition
(a) Both asserti on (A) and reason (R) are true and reason (R) i s the correct
expl anati on of asserti on (A).
(b) Both asserti on (A) and reason (R) are true but reason (R) i s not the correct
expl anati on of asserti on (A).
(c) Asserti on (A) i s true but reason (R) i s f al se.
(d) Asserti on (A) i s f al se but reason (R) i s true. |
|
|
Term
Asserti on -D i l uti on of any col ored compound i n water shows l i ght col or than
ori gi nal col or of compound.) (hi nt- potassi um permanganate di ssol ve i n
water)
Reason - Compounds do not show light color.
l |
|
Definition
(a) Both asserti on (A) and reason (R) are true and reason (R) i s the correct
expl anati on of asserti on (A).
(b) Both asserti on (A) and reason (R) are true but reason (R) i s not the correct
expl anati on of asserti on (A).
(c) Asserti on (A) i s true but reason (R) i s f al se.
(d) Asserti on (A) i s f al se but reason (R) i s true. |
|
|
Term
Asserti on -Dilution of any colored compound in water shows light col or than
original color of compound.) ( hi nt- potassi um permanganate dissolve in water)
Reason-when dilution is done by water the quantity of particle getti ng decreases
by dilution hence it shows light color. |
|
Definition
(a) Both asserti on (A) and reason (R) are true and reason (R) i s the correct
expl anati on of asserti on (A).
(b) Both asserti on (A) and reason (R) are true but reason (R) i s not the correct
expl anati on of asserti on (A).
(c) Asserti on (A) i s true but reason (R) i s f al se.
(d) Asserti on (A) i s f al se but reason (R) i s true. |
|
|
Term
Asserti on- Particles in liquid state show motion.
Reason -It possess kinetic energy. |
|
Definition
(a) Both asserti on (A) and reason (R) are true and reason (R) i s the correct
expl anati on of asserti on (A).
(b) Both asserti on (A) and reason (R) are true but reason (R) i s not the correct
expl anati on of asserti on (A).
(c) Asserti on (A) i s true but reason (R) i s f al se.
(d) Asserti on (A) i s f al se but reason (R) i s true. |
|
|
