CHEMISTRY
CLASS VIII
CHAPTER 4
TRANSFORMATION OF SUBSTANCES
CHAPTER - 4
TRANSFORMATION OF SUBSTANCES
PART -A
EXERCISE - I
PAGE- 79
Q-1 a) freezing
b) melting point
c) chemical
d) composition
e) exothermic
Q-2 a) physical change;A physical change is a temporary change in which no new substance is formed and the
chemical composition of the original substance remains same .ex- melting of ice.
b) Chemical change;A chemical change is a permanent change in which new substance is formed whose
chemical composition and physical and chemical properties are different from those of the
original substance ex;- curdling of milk
Q-3 a) physical change
b) physical change
c) chemical change
d) chemical change
e) physical andchemical change
f) chemical
g)physical
h) chemical
Q-4 a) When zinc reacts with dilute hydrochloric acid hydrogen gas is evolved with
effervescence.
Zn + 2HCl → ZnCl2+H2↑
b) when iron pieces are added to blue solution of copper sulphate the colour of the
solution changes to green
Fe +CuSO4→ FeSO4+Cu
c) when hydrogen sulphide gas and chlorine gas reacts they produce solid sulphur and
hydrogen chloride gas
H2S(??? Cl2???→ ???????? S(s)
Q-5 Burning of a piece of magnesium is not a physical change because when magnesium burs a
new substance magnesium oxide is formed with increased weight.
2Mg? O2→2MgO
Q-6 Adding of sodium to water is a chemical change because during this process hydrogen gas
is evolved with effervescence and heat is evolved which ignites the hydrogen
2Na ?2H2O→ 2NaOH ? ? 2↑
Q-8 Exothermic reactionsA chemical reaction in which heat is given out is called exothermic reaction. Ex1) C? O2→CO2?ℎ???
2) CaO ?H2O→ Ca(OH)2?ℎ???
Endothermic reactionsA chemical reaction in which heat is absorbed is called endothermic reaction.
1) N2?O2?ℎ???→2NO
2) CaCO3?ℎ???→ ??? ? ??2
Q-9 a) Freezing of water to ice and evaporation of water both are physical changes because
during both changes the chemical composition of water remains same and no new substance is
formed only the state of water is changed.
On freezing water changes from liquid to solid .
On evaporation water changes from liquid to gas.
b) A glass tube is broken into pieces is a physical change because on breaking there is no
change in the composition of glass only the shape and size of the tube is changed.
c) Burning of a candle is both a physical and chemical change –
when candle burns the wax melts and resolidify which is a physical change.
When the wax around the wick melts rises up and vaporise to form carbon dioxide and water
vapour is considered to be a chemical change.
Q-10 An endothermic reaction causes fall in the temperature of the surroundings while an
exothermic reaction causes rise in the temperature of the surroundings.
Q-11 a) a catalyst is a substance which alters the rate of a chemical reaction without
participating in the chemical reaction.
b) (i) When a catalyst increases the rate of a chemical reaction it is called a positive
catalyst’
ex- manufacture of ammonia takes place speedly with nitrogen and hydrogen in
presence of iron catalyst
(ii) When a catalyst decreases the rate of a chemical reaction it is known as negative
catalyst.
ex- decomposition of hydrogen peroxide takes place slowly in presence of phosphoric
acid.
c) the three biochemical catalyst found in human body are – trypsin, amylase , and pepsin
Q-12 a) when dilute sulphuric acid is added to granulated zinc hydrogen gas is evolved with
effervescence’.
b) when a few pieces of iron are added in a blue solution of copper sulphate the colour will
change to green.
c) when silver nitrate is added to an aqueous solution of sodium chloride a white
precipitate of silver chloride will form.
d) when ferrous sulphate solution is added to an aqueous solution of sodium hydroxide a
dirty green precipitate of ferrous hydroxide will form.
e) when solid lead nitrate is heated strongly reddish brown vapour of nitrogen dioxide will
evolve.
f) when calcium bicarbonate solution is heated carbon di oxide gas will evolve which will
turn lime water milky.
Q-13 a) N2??2→2NO
b) H2S???2→ ????? ?
c) 2Na??? 2O→ ????? ? ? 2
d) NaCl ?????3→ ????? ????3
e) Zn??2SO4→ZnSO4??2
f) FeSO4?????? → ??????2???2SO4
h) 2Pb(NO3)2→ ???? ? ???2??2
h) Ca(HCO3)2→ ????3??2O???2
EXERCISE II
I FILL IN THE BLANKSA) COMBINATION
B) CATALYST
C) EFFERVESCENCE
D) NEUTRALISATION
E) OXIDATION
F) DISPLACEMENT
G) DOUBLE DECOMPOSITION
H) INCREASES /DECREASES/UNCHANGED
I) COMBINATION (SYNTHESIS)
J) REDUCTION
II CLASSIFY THE FOLLOWING REACTIONS AS COMBINATION, DECOMPOSITION, DISPLACEMENT,
PRECIPITATION AND NEUTRALIZATION. ALSO BALANCE THE EQUATION.
a) Decomposition
b) Displacement
c) Precipitation
d) Combination
e) Precipitation
f) Displacement
g) Combination ( 2Ca ?O2→ ????)
h) Neutralization
i) Neutralization (2KOH ? ?2SO4→ ?2SO4? ?2O
3. Classify the following as oxidation or reduction and complete the equationa) Fe2+- e-→ ??3+
b) Cl+e-→ ??c) Na – e-→ ??+
d) Cl- - e-→ Cle) Al3++3 e-→ ??
f) Hg2++ e-→ ??+
g) O+2e-→ ?2Definea) Precipitation:-
A chemical reaction in which two compounds in their aqueous state react to form an
insoluble salt ( a precipitate) as one of the products is known as precipation reaction.
b) Neutralization:A chemical reaction in which a base or an alkali reacts with an acid to produce a salt and
water only is known as neutralization .
5) Redox reactionA reaction in which oxidation and reduction take place simultaneously is called redox
reaction, i.e. one substance is oxidized and the other substance is reduced at the same time.
For ex;When chlorine reacts with hydrogen sulphide, chlorine gets reduced to hydrogen chloride and
hydrogen sulphide gets oxidized to sulphur.
Cl2? ?2S→ ?????S
6)
a) combination reaction:A reaction in which two or more substances combine to form a single substance is called
combination reaction.
Ex- Fe+ S→ ???
C + O2→ ??2+ heat
b)decomposition reaction:A reaction in which a compound breaks up due to the application of heat into two or more
simple substances is called decomposition reaction.
Ex- 2HgO→ ???? ?2
2H2O→ ?? 2 + O2
c)Displacement reaction:A reaction in which a more active element displaces a less active e;ement from a compound is
called displacement reaction.
Zn + 2HCl → ZnCl2+ H2
Zn + H2O→ ??? ? ? 2
d)Doubl e decomposition :A chemical reaction in which two compounds in their aqueous state exchange their ions to form
new compounds is called a double decomposition reaction.
AgNO3 + NaCl → ????? ????3
NaOH + HCl → NaCl + H2O
7) write the missing reactants and products and balance the equations:a) PbO + H2→ ?? ? ?2O
b) NaOH +HCl→ NaCl + H2O
c)2 KClO3→ ????+3O2
d) NaHCO3+ HCl→ ????? ?2O +CO2
8) How will you obtain/
a) Magnesium oxide can be obtained from magnesium by burning magnesium in presence of
oxygen which will produce magnesium oxide with dazzling light . 2Mg + O2→ ?? ??
b) silver chloride can be obtained from a silver nitrate by mixing aqueous solutioin of silver
nitrate and sodium chloride.AgNO3+ NaCl→ ????? ????3
c) Nitrogen dioxide can be obtained from lead nitrate by heating it strongly and it will
decompose to give nitrogen di oxide. 2Pb(NO3)2→ ???? ? ???2+ O2
d)Zinc chloride can be obtained from zinc by adding zinc granules in dilute hydrogen chloride.
Zn + 2HCl → ????2 + H2
e) Ammonia can be obtained from nitrogen by heating mixture of nitrogen and hydrogen under
pressure in presence of iron catalyst.
N2? H2→ ??? 3
9) oxidation:1) it is a process which involves addition of oxygen.
2) it can also be explained by removal of hydrogen.
3) it involves loss of electrons.
4) oxidation Is generally shown by metals which form positive ions.
Reduction:1) It is a process which involves addition of hydrogen.
2) 2) it can also be explained by removal of oxygen.
3) It involves gain of electrons.
4) Reduction is generally shown by non metals which form negatively charged ions.
10)
a) when iron nail is kept in copper sulphate solution the blue colour of copper sulphate will
change to green due to formation of ferrous sulphate.
b) when phenolphthalein is added to sodium hydroxide solution it will turn pink.
c) When blue litmus paper is dipped in dilute hydrochloric acid the blue colour of litmus paper
will change to red.
d) when lead nitrate is heated reddish brown nitrogen dioxide gas will evolve.
e) when magnesium ribbon is burnt white powder of magnesium oxide will form.
f)When ammonia is brought in contact of hydrogen chloride gas white powder of ammonium
chloride will form.
11) give reasonsa) a person suffering from acidity is advised to take an antacid like milk of magnesia because it
is basic in nature and neutralize the effect of acidity.
b) acidic soil has disturbed pH value ( less than 7) which can be made normal (pH 7) by adding
quick lime (CaO) which is basic in nature and neutralize acidity.
c) wasp sting are alkaline in nature which can be neutralized by applying vinegar which is a
weak acid ( acetic acid).
Chapter 4
Transformation of substances
Part—C
ELECTROLYSIS
EXERCISE III
1) DEFINE THE FOLLOWING TERMS:a) Electrolysis :Electrolysis is the process in which an electric current is passed through the aqueous
solution of a compound or its molten state to bring about a chemical change.
b) Electrolyte:-
Electrolytes are the aqueous or the molten compounds that conduct electric current
and get decomposed into respective ions.
c) Cathode:The electrode connected to the negative terminal of the battery is called cathode.
d) Anode:The electrode connected to the positive terminal of the battery is called anode.
e) Cation:Cations are the positively charged ions.
f) Anions :Anions are the negatively charged ions.
2) Differentiate between:
Cation and anion:Cation
Anion
1)cations are positively
1) Anions are negatively charged ions.
charged ions.
2) During electrolysis anions migrate
2) During electrolysis cations
towards the anode.
migrate towards the cathode.
Examples:Examples:-Cl-,OH-,Br-etc.
Na+,Ba2+,Ca2+etc.
Anode
1) The electrode connected to the
positive terminal of the battery is
called anode.
2) Current enters the electrolyte
through the anode.
3) Anions migrate and discharge at
the anode.
Electrolyte
Electrolytes are the aqueous or the
molten compounds that conducts
electric current and get de composed
into respective ions.
Examples- acids ,bases and salts are
electrolytes
Cathode
1) The electrode connected to the negative
terminal of the battery is called cathode.
2) Current leaves the electrolyte through the
cathode.
3) Cations migrtate and discharge at the
cathode.
Non electrolyte
Non electrolytes are the aqueous or molten
compounds that do not decompose into ions and
thus do not conduct electric current.
Examples – sugar, pure water,alcohol etc are non
electrolytes
3)Give two examples for each of the following
a) strong electrolyte:- sodium chloride, potassium chloride
b) weak electrolyte:- Ammonium hydroxide, acetic acid
c) non electrolytes :-sugar , pure water
d)substance used to make electrode :- metals or graphite
4) Applications of electrolysis:- The main applications of electrolysis are:1) electroplating:-It is the process of plating a metal or an article with another metal.
2) electrorefining :- It is the process of refining an impure metal to obtain its pure form.
3) electrometallurgy( extraction of metals) :- It is the process of extracting a metal in its pure
form from compounds containing that metal.
5) Electroplating is an electrolytic process in which the deposition of a superior metal is done on
the surface of an inferior metal or an article.
In electroplating of an article by silver :Cathode:- the article to be electroplated
Anode:- metal plate made up of pure silver
Ion present in the electrolyes are:K+and Ag+ions
6)
a) electrolysis of molten sodium chloride:reaction at cathode:- Na++
CHAPTER 5
METALS AND NONMETALS
Q 1 FILL IN THE BLANKS:1) free
2) Fe2O3
3)electrolysis
4) alloy
5) copper ; tin
6)malleable
7) cations
8)4 to 7
9) metal
10) acidic ; neutral
Q2 a) (iii)
b) (ii)
c) (ii)
d) (ii)
e) (i)
Q3 true or false
a) false
packaging of food stuff
b) false hydrogengas
c) true
d) false wrought iron
e) false accepts
f) false liquid metal at above 30 degrees temperature
g) false neutral
h) true
Q4 name the following:a) magnetic separation
b) stainless steel
c) brass and bronze
d) metal is mercury and non metal is bromine
e) water and carbon monoxide
f) hydrogen and ammonia
g) hydrogen
h) salt and water
i) sodium and potassium
Q5 a)4 Na + O2→ 2Na2O
b) 2K + 2H2O→ 2KOH + H2
c)Zn + 2HCl →ZnCl2 + H2
d) Fe + CuSO4→FeSO4 + Cu
e) CO2 +2 NaOH→ Na2CO3 +H2O
Q6 a) Bauxite :Formula :- Al2O3.2H2O
Name :- Hydrated Alumminium oxide
b) Heamatite:formula :- Fe2O3
Name :- Ferric oxide
c) Galena :Formula:- PbS
Name :- Lead sulphide
d) Cinnabar:Formula :- HgS
Name :- Mercury sulphide
e) Marble :Formula :- CaCO3
Name :- Calcium carbonate
Q 7 Give two important uses of the following metals and non metals :a) Gold:- 1) in the manufacture of electronic devices like telephones, computers, etc.
2) making ornaments and coins.
b) Silicon:- 1) in making microchips for computers.
2) silicon is used in the manufactureof “ silicone”, a water proof material.
c) Iron :- 1) in manufacture of radiators, railings, mainhole lids and drain pipes
2) power transmission towers
d)Copper :- 1) in making electric wires and cables, utensils and semi- precious ornaments.
2) electronic devices.
e) Sulphur:- 1) in manufacture of chemicals like , sulphuric acid , sodium thiosulphate , gun
powder, dyes etc.
2) to prepare skin ointment ( fungicide).
Q 8 Define the following :a) Metallurgy:- The scientific principles and the physical and chemical processes that are
applied to obtain pure metals from their ores are known as metallurgy.
b) Gangue:-Earthly impurities like sand , clay and mud, when they are present in an ore, are
called gangue or matrix.
c) Ore:- An ore is a type of mineral from which elements or compounds can be extracted
economically.
d) Roasting:- Heating of ore strongly in presence of air. Mainly done for sulphide ores
e) Calcination :- Heating of ore strongly in absence of air. It is mainly done for carbonate ores.
f) Slag :- The substance formed by the chemical combination of flux and ore based impurities is
called slag.
g)Flux:- The substance added to the ore to remove impurities during the reduction of oxidized
ore from primary ore is called flux.
h) Smelting:- The process of removing oxygen from a metallic oxide so as to convert it into a
metal is known as reduction or smelting.
i) Indicators:- Organic compounds used to ascertain the nature of a solution ( whether acidic ,
basic or neutral).
Q 9 An alloy is a solid homogeneus mixture of usually two metals or metals and non metals.for
ex:- Brass, bronze, steel etc.
Alloy of iron:Steel
Uses of steel:- for making rails, bridges, ships tanks etc.
Alloy of Alluminium :Duralumin
Uses of Duralumin:- for making aircraft bodies , light tools pressure cooker etc.
Alloy of Zinc :Brass
Uses of brass :-for making statues , screws, and handles, utensils machine parts and decorative
articles.
Q 10Physical properties of metals and non metals:1) lusture
lusturous
Non lusturous
2) melleability
malleable
Non malleable
3)conductivity
Good conductor
Bad conductor
4) ductility
Ductile
Non ductile
5)solubility
usually insoluble in water
no fixed rules applied
Q11 A list in which the metals are arranged in the decreasing order of their chemical reactivity
is called the metal reactivity series.
Its important features are:-
1)Tendency of losing eletrons and forming cations also decreases down the series
2) hydrogen being a non metal also included in the series because it also shows loss of electon
and form cation.
3)the series facilitate the comparative study of metals in terms of the degree of their reactivity.
4)the compounds of metals can also be compared.
Q12 differentiate:a)Ore:A type of mineral from which elements or compounds con be extracted economically
Some commom ores are Bauxite, Heamatite,Magnetite etc.
Minerals:The naturally occurring compounds of metals mixed with earthly impurities like sand , clay,
stone etc.,are called minerals. All the minerals are not considered as ore of that metal.
b) calcination :the process of strongly heating a concentrated ore in the absence of air to a temperature that is
sufficient to melt the ore is known as calcinations.
It is mainly done with carbonate ores to convert them into metallic oxide.
Roasting:The process of heating concentrated ore to a high temperature in exess of air is known as
roasting .
It is mainly done with sulphide ores to convert them into metallic oxide.
Q13 For electrorefininng thick rod of impure metal is taken as anode and thin rod of pure metal
as cathode .the two electrodes are dipped in the electrolyte which contain the ions of the metal
that is to be refined.
When electric current is passed through the electrolyte , it dissociates into free metal ions and
thus pure metal gets deposited at the negative electrode i.e cathode and impurities are settle
down as anode mud below the anode.
Q14name:a) Metallurgy
b) zinc oxide
c) Haematite Fe2O3 Magnetite Fe3O4
Q16 An oxide is a compound which essentially contains oxygen in its molecule, chemically
combined with a metal or a nonmetal.
They are of two types:- metallic oxide and non metallic oxide.
Two examples in each:a) Basic oxide:- Na2O ,K2O
b) Acidic oxides:- CO2, SO2
c) Amphoteric oxides:- ZnO ,PbO
d) Neutral oxide:- H2O, CO
GEOGRAPHY
CHAPTER-10
INDIA – PHYSIOGRAPHIC DIVISIONS
A. Answer the following questions in brief:
1. Longitude: 68o7’ and 97o25’
Latitude: 8o4’ and37o6’
2.
3.
4.
5.
6.
Tropic of Cancer
A land mass bounded by the sea on three sides is called peninsula.
821/2o East longitude.
India and Myanmar.
On the basis of the relief features, India can be divided into the
following physical divisions:
I.
The great mountains of the north
II. The northern plains
III. The peninsular plateau
IV. The coastal plains
V. The great Indian desert
VI. The islands
7. I. The Karakoram
II. The Himalayas
8. Kanchenjunga
9. The Narmada River
10.
Anai Mudi, Kerala
11.
Malwa plateau is bounded by Aravali Range, the Vindhya
Range and the Chotta Nagpur plateau.
12.
The Malabar Coast.
13.
The Sunderban delta
14.
It extends from the river Subarnarekha in the north to
Kanyakumari in the south.
(B) Answer the following questions in detail:
1. Longitude: 68o7’ and 97o25’
Latitude: 8o4’ and37o6’
India is situated in the southern part of Asia at the head of
the Indian Ocean.
2. These mountains streatch from Kashmir in the west to
Assam in the east and form an arc. They are about 2500
km long and 160 to 450 km wide. They are the young fold
mountains.
3. The great plains of north India constituted by two large
river basins. They are The Indus river basin and The GangaBrahmaputra basin. The Indus river basin is drained by the
Indus and its tributaries Jhelum, Chenab, Beas, Ravi and
Sutlej. The Indus basin Ganga and its tributaries like
Yamuna, Ghaghra, Gandak and Kosi rivers. The eastern
most part of the Great Plains is formed by the
Brahmaputra valley.
4. The peninsular plateau is made up of ancient igneous and
metamorphic rocks. This plateau is divided by the
Narmada River into two parts: the Malwa plateau and
Deccan plateau.
5. The Ganga-Brahmaputra delta is the largest delta. It is
situated in West Bengal and Bangladesh. It is one of the
fertile areas in the world.
(C) Distinguish between the following:
1. Western Ghats
I. These ghats rise steeply from the west coast.
II. The hills of the Western ghats are continuous.
III. All the rivers of the Deccan plateau rise in the wetern
ghats.
Eastern Ghats
I. These ghats rise gently from the east coast.
II. The hills of the Eastern ghats are continuous.
III. Most of the rivers cut valleys through the Eastern Ghats.
2. The western coast
I. The coast stretches from Rann of kachchh in the north to
Kanyakumari in the south.
II. The coast is narrow and uneven.
Iii The coast has estuaries and lagoons.
The eastern coast
I.
It extends from the river Subarnarekha in the north to
Kanyakumari in the south.
II. The coast is wider and more leveled as compared to
Western coast.
III. It has fertile deltas of rivers.
3. The mountains of Northern India
I. altitude is higher.
II. located in the northern boarder of India.
III Many perennial rivers are originated from these mountains.
Hills of peninsular India
I. These are in low altitudes.
II. They are located in the peninsular India.
III. Non perennial rivers are flowing here.
4. The Himachal
I. they are the mountain ranges from 4000m. to 4500m.
II. they are middle ranges in the Himalayas.
The Himadri
I.
II.
They are the lowest ranges in the Himalayas.
Located in the southern part of the Himalayas.
CHAPTER-10
INDIA – CLIMATE
A. Answer the following questions in brief:
1. Latitude, Himalayan Mountains, distance from the sea.
2. There are four distinct seasons in india. They are:
I.
The cold weather season
II. The hot weather season
III. The season of the advancing monsoon
IV. The season of the retreating monsoon
3. Maritime climate
4. Western disturbances
5. Tamil nadu, Punjab and Haryana
6. Loo is a hot, dry and dusty local wind blow over northern plains.
7. Kerala and Karnataka.
8. The Arabian Sea branch and the Bay of Bengal branch.
9. Mawsynram near Cherrapunji in Meghalaya.
10.
It is due to high temperature and humidity. The high
temperature in this month is often called the ‘October heat’.
11.
The southern slopes of the eastern Himalayas, Assam, West
Bengal and east coast receive heavy rainfall.
12.
Northern part of Kashmir, Western Rajasthan and interior
parts of Deccan Plateau are areas of low rainfall.
(B) Answer the following questions in detail
1. During winter, Himalaya protects us from the cold
winds from Siberia. During summer, Himalaya stops the
moisture bearing clouds and bring rainfall in the southern part
of the Himalayas.
2. The season of advancing monsoon continues till
September. October and November is the time of retreating
Monsoon. In the month of October we experience the October
heat. November to February is the time of cold weather season.
India enters into summer from March onwards.
3. Monsoon winds are mainly responsible for rain in India.
All agricultural activities in India depend on the monsoon
rainfall.
4.
They blow during the months of June to September.
It has two branches: i.e. the Arabian Sea branch and bay of
Bengal branch. Another characteristic of the monsoon is the
oppressive heat and humidity known as ‘October Heat’.
5.It is the temperature cyclones experienced over northern
India during winter season. It is originate in the Mediterranean
Sea.
VIII - A BIOLOGY
short answer...
ans 1 - it causes the serious damage to the nervous systm...
it has a bad effect on vision, hearing capacity.
ans 2- functions..
calcium- to prevent tooth decay and bones strong because
of calcium.
iron- produced heamoglobin and increase weight .
ans 3- the blood glucosen level increase and it is also passed
with urine . diabetic persons suffer from excessivr thirst ,
frequent urination , fatigue and loss of weigtght.
long answer...
ans 1...
1. immunization -- it is the term used for introducing dead or
weakened microbes in the body of living beings for developing
immunity.
2. prevention of deficicency diseases -- alwyas eat balanced
diet.
3. personal hygiene -- taking care og one's own body is called
personal hygiene .
4. healthy habits -- the maintenance of healthy environment is
of great importance to prevent the spread of desiese .
5. healthy habits .
ans 2...
1.droplet infection
2. contaminated water we drink
3.contaminated food we eat
4. direct contect infection
5. vector
6.animal bites.
ans 3...
1. malformation of bones ..the bones become porous and
breaks easily.
2. improper functioning of kideny-- due to kideny failure there
is accumulation of toxic substances in the blood which is fatal.
3. improper functioning of eye lens --myopia , hypermetropia
and catract.
ans 4.. for cuts-- try to remove dirt from wound and clean the
skin around it with small pads of cotton soked in an antiseptic
solution.cover the wound with a clean cotton dressing tom stop
bleeding.
for burns-- for minor burns keep the burnt are3a under
cold water for few minutes then apply an antiseptic cream like
burnol on burnt part.
for severe burns-- in this case take the patient to the dorctor
immediately .
for chemical burns -- wash affected area with water then
give first aid same as for the other burns .
COMPUTER
10.STATIC ELECTRICITY.
E. Short answer type questions.
1 .It is a device to detect the presence of charge. It can be two types. Pith ball electroscope and
gold leaf electroscope.
2. Same charge will repel and opposite charge will attract.
3. Detect the presence of charge and find the nature of charge.
4. The massive flow of charge between two oppositely charged clouds is known as lightning.
The rapid expansion and contraction of air produces a cracking sound known as thunder.
5. It is a device used to protect tall buildings from the dangers of lightning.
F. Long answer type questions.
1. Atom having nucleus at its centre which contain positively charged protons and charge less
neutron. Around the nucleus negatively charged electrons revolved in orbital.
2.When glass rod rubbed with silk, glass rod lost electrons ,hence it become positively charged
.On the other hand silk gained electrons hence become negatively charged.
3. Page number.126
4. By touching it with negatively or positively charged materials.
G. Challenge questions.
1. By making aeroplane earthed.
2. Chaged dust particles will attracted towards the oppositely charged rods.
11. ELECTRICITY AND MAGNETISM.
E. Short answer type questions.
1.
(a) Number of turns.
(b) Amount of current.
(c) Diameter of the core.
2. Whenever there is a flux change induced emf will produce hence induced current too.
3. Whenever there is a flux change induced emf will produce hence induced current too.
Faraday’s law : page number: 142.
4. Electromagnetic induction.
5. A current carrying conductor placed in a magnetic field will experience a force. Electric motor
used in water pumps ,washing machines, mixer grinders and refrigerators.
F. Long answer type questions.
1. (a) Attraction is maximum at poles.
(b) Directive property.
(c) Attractive and repulsive property of poles.
(d) Magnetic poles always exist in pairs.
2. Page number: 133
3.
* Used in telephones, electric motor and electric bell.
* To lift heavy loads.
* Bullet trains.
* Audio and video tapes.
* Preparation of permanent magnets.
4. An insulated copper wire wounded over a cylindrical tubes behaves like a bar magnet when an
electric current flows through it is called a solenoid. Clock wise current will produce south pole
and anti clock wise current will produce north pole.
5. Page number: 136
6. When a bar magnet is moved towards the coil the galvanometer shows some deflection. When
magnet is completely inside the coil the galvanometer shows null deflection. When magnet
moved away from the coil, galvanometer again shows deflection.
7. A transformer is a device used to increase or decrease the voltage of an ac source.
Transformers are of two types (a) Step up transformer and (b) Step down transformer. Uses
given in page number :144
G . Challenge questions.
1. Magnetic lines of force are very close to each other near to the poles , hence attraction is
maximum at the poles.
2. Magnets are used in the TV as a deflection plates to guide the electron beam to a particular
target.
COMPUTER
8) DECISION CONTROL STRUCTURES
1. Explain the use of if control structure?
The if statement is used to check a specific condition. It performs a course of action if the
condition is true; otherwise, it ignores the action.
2.
What is the unique feature of for loop?
For loop is used to repeat a particular task for finite number of times. It performs a fixed
number of iterations, which are specified in a counter variable which in turn keeps a track
of the number of iterations.
Syntax:
For(initialization expression(1);conditional expression(2);increment/decrement expression (4))
{
Java statements(3)
}
3. State the difference between Entry and Exit controlled loop. Give one example of each?
For loop also called Entry controlled loop. because the body of the loop is executed only
after the condition evaluations to true. The loop will never be executed if the condition is
false in the beginning.
Example:
Class Number
{
Public static void main(String args[])
{
int a;
for(a=1;a<=10;a++)
{
System.out.println(a);
}
}
}
Since the do while loop checks the condition after execution the block of statement, so do
while loop is considered as an Exit control loop. The program gets executed at least once
even if the condition is evaluated to false.
Example:
Class Alphabets
{
Public static void main(String args[])
{
int i=1;
char a=’G’;
do
{
System.out.println(a);
i++;
a++;
}
while(i<=10);
}
}
4. Explain the switch statement with an example?
The switch statement is used when there is a requirement to check multiple conditions in
a program. It provides an easy way to branch to different parts of the code in a program
based on the value of an expression. If none of the case matches the compiler executes
the statements written in the default case.
Example:
Public class message
{
Public static void main(int value)
{
System.out.println(“enter value is”+value)
Switch(value)
{
Case 1:
System.out.println(“hi”);
Break;
Case 2:
System.out.println(“hello”);
Break;
Default:
System.out.println(“no match found”);
}
}
}
5. What is the importance of break statements in switch?
The break statement inside the switch statement is used to terminate the statement
sequence.
The default case is the last statement of the switch case. It is an optional statement. It
executes only when the values stored in switch expression does not match any case.
6. Give one difference and similarity between for,while and do while loop?
∑
For loop is used to repeat a particular task for finite number of times. It performs a
fixed number of iterations, which are specified in a counter variable which in turn
keeps a track of the number of iterations
∑
The while loop repeats a statement or block of statements till the specified condition
remains true. It tests the condition before executing the loop body.
∑
Since the do while loop checks the condition after execution the block of statement,
so do while loop is considered as an Exit control loop. The program gets executed at
least once even if the condition is evaluated to false.
9) UNDERSTANDING HTML
1. What is HTML?
HTML is a complete code package that allows a user to create web pages. It include text
and graphics. You can add links to your web pages. Hyperlinks are the highlighted text
segments or images that connect a page to other pages on the web.
2. What do you understand by tags? How many types of tags are there?
A tag comprises of text enclosed in angle brackets< >. All tags have their own attributes
and default values. Each tag in HTML follows specific rules known as syntax. These tags
are not case sensitive. For example <tag name> and <TAG NAME> will have the same
effect.
¸ Container tags
¸ Empty tags
3.
Differentiate between container tag and empty tag?
Container elements: In html . the tag include both on and off tags are called container
elements. A tag is opened using opening angle brackets< > and closing brackets </>
For example <html> tag its closing tag which is </html> and attribute as well.
Empty elements: empty elements contain only on tag. They do not have off tags.
Example <BR>
4. Which attributes of <BODY> tag are used to set margins in a web pages?
The top margin attribute is used to set the top margin of web page. It is given within the
<body> tag with any value such as 60. This will display the text 60 pixels away from the
top the page.
<body topmargin =”value”>---------</body>
5. What do you understand by attributes in html?
An attribute is a property value that modifies an Html element. Attributes appear inside
the opening tag and their value is away inside the quotation marks.
For example : <font size=4 , color =”blue”> here size and color are the attributes of the
<Font>tag.
6. Explain the paragraph tag and its attributes?
Any text containing more than a few lines should be given inside the paragraph tag. We
use the <p> tag to display text in the form of a paragraph. To mark the end of a
paragraph </p> element is used.
7. What is the significance of BGCOLOR attribute of <BODY> tag?
This attribute is used to change the background colour of the web pags. In the <body>tag,
type bgcolor=”?”, replacing ‘?’ with the name or a color code.
Syntax:<body bgcolor=”red”>
8. What is the significance of <BR> tag?
This tag break the line and display the text from the next line. Without giving any space
between two lines. It should be given at the end of the line after which a new line is
required.
9. Which tags are used to apply the bold underline and italic properties to the text?
Bold: the bold tag is used when you want to emphasise the text. Type <b> before the text
which you want to display as bold and type</b> after the text.
Italic: To divert the attention of the reader on any important ,italic element is used. This
element marks up the text in italic style. Typing the text between <i> and</i> tags will
change the text in italics.
Underline: this tag underlines the text enclosed in <ul>and</.ul>tags.
10) USING LIST AND CREATING A TABLE
1. What is a table and what is its significance in HTML?
Tables arrange data in rows and columns and provide an attractive way to represent
information .tables are created to
∑
Present information or data in a compressive manner
∑
Make comparative analysis of data.
To create a table in html. We use the <table> tag. Each table begins with a <table>tag and
ends with </table>
2. What is the significance of <tr> and<td> tags in a table?
Each row within a table begins with the <tr>table row tag. And ends with the </tr>tag.
Rows must be inside the <table>tag. The columns contain cells. Each of which begins
with <td >table data tag and ends with </td> tag. Cells must be present inside rows.
3. Differentiate between cell padding and cell spacing ?
∑
This attribute sets the margins within a cell. It create a distance between the edge of
the cell and the contents of the cell. It is the pixel space inside the cells ie the distance
between the cell contents and the cell boundary.
∑
This attribute is used to set the minimum distance two adjacent cells. Cell spacing is
measured in number of pixel between the table cells.
4. What is the difference between Bordercolor and Bgcolor attributes?
∑
The Border color attributes is used to set the color of a table. The default color of the
border is gray but we can change it by assigning a different color name code to the
bordercolorattribures.
∑
The bgcolor attribute is used to set the background color of a table. The default color
of the background is gray. We can change it by defining a color name or hexadecimal
code.
5. How will you create a link on a web page?
To create a hyperlink <A>(Anchor) tag is used. The HREF attribute of the <A> tag stores
the reference of the document that is to be linked. The text that appears on the hyperlink
is enclosed between the starting tag</a> and ending tag</a>
Syntax: <a href=”document name”>hyperlink text</a>
6. Difference between ordered and unordered list?
∑
An unordered list is used when the items are not to be displayed in any particular
sequence. The default bullet type for most web browser is disc. Before the list of
items. The list begins and ends with<ul> and </ul> tags respectively .
∑
The ordered list is used to display the list of items in a specific order. By default
numbers are displayed in a web browser when an ordered list is used. We can change
the style using the type attribute.
CHAPTER- 6
SHORT ANSWER--
ans 1-- water and air
ans 2-- burning of fossil fules , automobiles, acid fumes,
volcanic toxic gases smoke and dust are the main air
pollutants .
ans 3--coal and petrol
ans 4-- we can conserv wild life in following ways -wild life protection act
protection of natural habitate
prevent deforestation
LONG ANSWER QUESTION----
ANS 1--it causes soil erosion . deforestation causes change in
rain fall pattern . burning of wood obtained from deforestation
causes increase in the concentration of carbon di oxide in the
atmosphere.
in the absence of trees of the forest the rainwater flows
faster causing fllod condition . deforestation causes adverse
climatic changes . in the absence of trees and plants the
animals will not get food and shelter .
ANS 2-- alternatives sources of energy..
solar energy-- the energy obtainted from the sun is called
solar energy.it is an inexhaustable source of energy
biomass energy-- biomass energy is derived from the waste
orn residues of animals and plants .
hydroelectric energy-- this type energy produced from the
water when it is flow down from a height to drive the turbine
connected to a generator .
tidal energy-- the energy obtained from tidal waves of the
oceans ans seas .
wind energy-- energy produced from wind is called wind
energy.
geothermal energy-nuclear energy--
ans 3-- method of prevention and control of water pollution-1. excessive use of fertilisers and pesticides should be
discouraged .
2. washing clothes , cleaning utensils, taking bath near
water bodies such as lakes and ponds should be restrected.
3. dead bodies should be cremated or buried and not
disposed off in a river or a lake .
4. educating the public about the harmful effects of water
pollution .
method of prevention and control of noise pollution--
1. automobiles should be fitted with silencers and soft
horns .
2. we should not play radio tele vision and stereo system
too loudly .
3. the horn of motor vechicles should not not be blown
unnecessarily .
4. avoid bursting fireworks that make loud noise .
ans 4-water conservation --1. avoid brushing teeth washing hands or cleaning utensils
with running water tap .
2. collected rain water in drums and use it to water the
plants .
3. use a bucket and mug instead of using a shwer for a
bath.
4. get leaking pipe lines and water taps repaired.
5. rain water harvesting .
6. reuse of water .
7. drip irrigation .
8. construction of dams.
soil conservation --1.by planting more trees and grass.
2. afforestation
3. preventing overgazing
4. step farming in hillyn areas
5. construction of dams.
ans 5 -1. a varity of trees growing in the forest like teak , shisham
, sal are sources of wood .
2. forest is a source of varity of products several plants are
source of medicenes .
3. forests maintain the natural balance of carbon di oxide
and oxygens.
4. forests prevents the soil erosion .
5. forests increse rainfall in the region .