Time
: 3 hours Max Marks: 80
SECTION 'A'
1.
(A) Answer the following. (5)
(i)
Fill in the blanks and rewrite the completed statements:. (2 Marks)
1.
The Chemical formula of POP is _____________ (2CaSO4H2O)
2.
Magnetic lines of force are __________ where the magnetic field is strong. (crowded)
(ii)
Complete the analogy. (2 Marks)
1.
CuCl2 + 2KI → CuI2 +2KCl : Double displacement ∷
Zn + 2HCl → ZnCl2 + H2 : _____________ (Displacement Reaction)
2.
Tungsten : Conductor ∷ Ebonite : _____________ (Insulator)
(iii)Name
the following : (1)
The
quantity expressed in coulomb.
(Electric charge)
(B) Rewrite the following statements by
selecting the correct options: (5 Marks)
1.
The second period contains ___________ elements.
a. 8
b.
2
c.
18
d.
32
2.
Eucalyptus oil is known as __________
a.
natural indicator
b. olfactory indicator
c.
synthetic indicator
d.
universal indicator.
3.
If a P.D. of 12 V is applied across a 3
Ω resistor, then the current passing through it is _______
a.
36 A
b. 4A
c.
0.25A
d.
15A
4.
When an object is placed between the focus and centre of curvature of a concave
mirror, then image formed is __________
a. real and magnified
b.
virtual and magnified
c.
real and of the same size as that of the object
d.
virtual and of the same size as that of
the object
5.
In dispersion of sunlight by a glass prism, ____________ ray is deviated the
least.
a. red
b.
yellow
c.
green
d.
violet
2.
Attempt the following. (10 Marks)
1. Elements in the same group show
the same valency.
i.
Valency is the number of electrons
given, taken or shared by an atom to complete its outermost shell.
ii.
All the elements in the same group
have the same number of electrons in their outermost shells.
iii.
Thus, all these elements take, give
or share the same number of electrons.
iv.
Hence, elements in the same group
show the same valency.
2. What is corrosion? Do gold
ornaments corrode? Justify.
Ans.
i.
The slow process of decay or
destructions of a metal due to the effect of air, moisture, acids, alkalies, or
other chemicals on it is called corrosion or rusting of iron. Its chemical
formula is Fe2O3.
H2O.
H2O.
ii.
Ordinarily, gold ornaments do not
get corroded.
iii.
Gold is one of the least reactive
metals. It does not react with air, moisture, sweat, or ordinary pollutants in
air or water. Hence, it does not get corroded.
3. State application (uses) of
baking soda.
Ans. The white amorphous powdered
soda is termed as baking soda. Its chemical name is Sodium Hydrogen Carbonate
or Sodium bicarbonate and its formula is NaHCO3. When tested with
litmus, NaHCO3 turns red litmus blue, which indicates that it is
alkaline in nature.
Sodium bicarbonate is extensively
used in day – to – day life.
i.
It is used to prepare light spongy
bread, cakes and dhokala.
ii.
It also helps to reduce acidity in
stomach being alkaline.
iii.
It is very useful in preparing CO2
gas and is one of the content of fire extinguishers.
4. Distinguish between, Conductors
and insulators.
Conductors
|
Insulators
|
1.
Those substances through which electricity can flow
are called conductors.
2.
Electrical resistances of conductors are very low.
3.
They contain large number of free electrons.
4.
Generally metals are conductors. E.g. silver,
copper, aluminium
|
1.
Those substances through which electricity cannot
flow are called insulators.
2.
Electrical resistances of insulators are infinitely
very high.
3.
They do not contain free electrons.
4.
Generally non – metals are insulators. E.g. wood,
rubber, plastic
|
5.
P and Q are the two wires of same length and different cross sectional
areas and made of same metal. Name the property which is same for both the
wires and that which is different for both the wires.
Ans.
i.
The property which is same for both
the wires is resistivity.
ii.
The property which is different for
both the wires is resistance.
6. Resistivity of some material is
given below. State which one will be the best conductor.
Material
|
Copper
|
Aluminium
|
Silver
|
Nickel
|
Resistivity
(Ωm)
|
1.62 x 10
– 8
|
2.63 x 10
– 8
|
1.60 x 10
– 8
|
6.48 x 10
– 8
|
From the above table we find that of all the
metals, silver has the lowest resistivity (1.60 x 10 – 8 Ωm), which
means that silver offers the least resistance to the flow of current through
it. Thus, silver metal is the best conductor of electricity.
3. Attempt the following (Any 5) . (15 Marks)
1. Fleming’s
Left hand rule:
Ans. Stretch
the forefinger, the central finger and the thumb of you left hand mutually
perpendicular to each other. If the forefinger shows the direction of the field
and the central finger shows the direction of the current, then the thumb will
point towards the direction of the motion of the conductor.
2. Give
scientific reasons:
Alloys like
alnico or nipermag are used in industry.
i.
Alloys like alnico or nipermag are very hard and are
used in the production of permanent magnets.
ii.
Permanent magnets of these alloys are used in
microphones, loudspeaker, ammeters, voltmeters, etc.
iii.
Alnico is an alloy of iron containing aluminium,
nickel and cobalt. Nipermag is an alloy of iron containing nickel, aluminium
and titanium.
iv.
Hence, permanent magnets prepared from these alloys
are most suitable for use in industries.
3. Distinguish between: Convex mirror and concave mirror.
Convex mirror
|
Concave mirror
|
1.
It is called as diverging mirror.
2.
The light is reflected from outer surface.
3.
It can form only a virtual image.
4.
According to sign convention, focal length is
positive.
|
1.
It is called as converging mirror.
2.
The light is reflected from inner surface.
3.
It can form a real image as well as virtual
image.
4.
According to sign convention, focal length is
negative.
|
4. Draw well
labeled ray diagrams for image formation
A ray diagram for object at
infinity for a concave mirror.
5. Explain how the formation of rainbow occurs.
Ans.
1. The beautiful
phenomenon of the rainbow is a combination of different phenomena – dispersion,
refraction and reflection of light.
2. The rainbow
appears in the sky after a rain shower.
3. The water
droplets act as small prisms.
4. When sunlight
enters the water droplets present in the atmosphere, they refract and disperse
the incident sunlight.
5. Then they
reflect it internally inside the droplet and finally again refract it.
6. As a collective
effect of all these phenomena, the seven coloured rainbow is observed.
6. Right hand thumb rule
Ans. Imagine
that you are holding a current carrying straight conductor in your right hand
such that the thumb points towards the direction current, then the curled
fingers around the conductor will give the direction of the magnetic field.
This is known as right hand thumb rule.
Q4.
Attempt the following (any 1) ( 5 marks)
1. Give Reason:
Stars twinkle at night.
Ans.
i.
The stars emit their own light and
they shine at night. The stars are point sources of light as they are very far
away.
ii.
During refraction of starlight from
the atmosphere, as starlight bends towards the normal, the apparent position of
the star is slightly higher then its actual position.
iii.
Also this apparent position of the
star is not stationary but changes slightly.
iv.
Because of mobility of air and
changes in the temperature, the atmosphere is not steady. Hence refractive
index of air in the given region goes on changing continuously and randomly.
v.
When the atmosphere refracts more
light towards us, the star is seen bright. When the atmosphere refracts less
light towards us, the star is seen dim. Thus due to change in the refractive
index of atmosphere, stars appear twinkling at night.
2. Find the expression for the
resistors connected in series
.
i.
Resistors connected
in series: - If the
number of resistance are connected one after another in such a way that the
same current flows through each resistance, then the arrangement is called
resistance in series.
1. LetR1, R2 and R3 are three resistances
connected in a series combination and let Rs be their effective resistance in the
circuit.
Let V1, V2
and V3 be the P.D. across resistances R1, R2 and R3 respectively. Let
‘V’ be the P.D. of the cell. Let ‘I’ be
the current flow through each resistance.
According to Ohm’s Law,
Conclusion: If the resistors are connected in series then.
i. In a circuit
the current is the same in every part of the circuit.
ii. The resistance
of the combination of resistors is equal to the sum of the individual
resistors.
iii.The total
voltage across the combination is equal to the sum of the voltage drop across
the separate resistors.
iv. The effective
resistance in a series combination is greater than the individual resistances.
v. This
combination is used to increase resistance in a circuit.
Section B
5.
(A) Say true or false with reason (5 Marks)
1.
Organisms that depend on other organisms for their food are called autotrophic
organisms.
Ans.
False: Organisms that depend on other organisms for their food are
heterotrophic organisms.
2.
Proteins are the body building nutrients.
Ans.
True.
3.
The resemblances and the differences are due to heredity.
Ans.
True.
4.
Multiple fission is carried out only during favourable period.
Ans.
False: Multiple fission is carried out only during unfavourable period.
5.
Covalent compounds are soluble in organic solvents.
Ans.
True.
(B)
Rewrite the following statements by selecting the correct options: (5 Marks)
1.
The division of cytoplasm through ________ plane is called simple binary
fission.
a.
transverse
b.
longitudinal
c. any
d.
diagonal
2.
__________ is a metalloid.
a.
Aluminium
b. Antimony
c.
Zinc
d,
Mercury
3.
Organs which are fundamentally the same in structure, but modified for widely
different functions are called known as _______ organs.
a.
analogous
b. homologous
c.
vestigial
d.
functionless
4.
__________ is the stalk of anther.
a.
Stamen
b.
Ovule
c. Filament
d.
Style
5.
Muscle cells contain special type of ______ which are capable of bringing about
change in their shape.
a.
starch
b. protein
c.
fat
d.
salt
6.
Attempt the following. (10 Marks)
1. How can we save energy in day to day life?
In day to day
life we can save energy by reducing the consumption of fuels. Reduction is
possible by efficient usage of energy, wastage elimination and awareness.
This can be
achieved by measures like:
i.
Controlling usage of electricity by using power saver
lamps and appliances.
ii.
Switching off the appliances when not in use.
iii.
Using public transport instead of private motorized
vehicles etc.
2. write a
short notes on Chipko movement:
i.
Chipko is a pioneering movement in environment
conservation in India.
ii.
It was first initiated in the Marwad region of
Rajasthan by the Bishnoi community.
iii.
The principle behind 'Chipko' is 'hug the tree' to
prevent it from being felled.
iv.
This simple principle was used in the Himalayas in the
1970s to protect the forest from contractors.
v.
When the forest was to be auctioned for timber
extraction, the local community started a 'Chipko movement' in that area and
protected the forest.
3. The use of
fossil fuels in villages.
The following
measures helps to reduce the use of fossil fuels:
i.
Rather than depend on fossil fuels, use energy from
renewable (non conventional) sources like solar energy, biogasplant, windmill
etc.
ii.
Different types of engines are being used for various
purposes. These engines are constantly consuming the sources of energy such as
coal, petroleum etc. To reduce the use of fossil fuels, engines that reduce
emissions to a large extent can be built and Compressed Natural Gas (CNG) can
be used.
4. In human beings
the gametes from the male parent decides the sex of the baby.
i.
In human beings there are 22 pairs
of autosomes and 1 pair of sex chromosome.
ii.
In human male gametes, two
dissimilar sex chromosomes XY are present whereas in females two similar sex
chromosomes XX are present.
iii.
All children inherit 'X' chromosomes
from their mother and 'X' or 'Y' from their father.
iv.
If it is X chromosome from father,
then the offspring will be a daughter and if 'Y' chromosomes, then it will be
son.
v.
Hence, the gametes from the male
parent decides the sex of the baby.
5. Short notes on Multiple fission
i.
During unfavourable
condition, the amoeba withdraws its pseudopodia, becomes almost round and
secretes a hard covering called cyst.
ii.
Inside the cyst nucleus
divides into many nuclei by repeated division, follow by division of cytoplasm.
iii.
As a result many daughter
cells are formed.
iv.
The cyst bursts to release
the daughter cells during favourable condition.
6. What does this log indicate? Write some names of
products on which you find this logo.
This logo indicates Recycle.
This logo is
found on plastic articles such as bottles, toys, furnitures, paper bags and
electronic equipments etc.
7.
Attempt the following. (10 Marks)
1.
Draw a well labelled diagram of: Longitudinal section of flower.
2. Write the functions of the following organs in reproduction.
1. Vagina
i.
It provides the route for
the menstrual blood to leave the body during menstruation.
ii.
It is a pathway through
which sperms enters into woman’s body.
iii.
It is a pathway through
which a baby comes out of the woman’s body during child birth.
2. Stigma
i.
It receives pollen grains
and on which pollen germinates.
3. Ovaries
i.
Ovaries develop and release
eggs into the oviduct.
ii.
It secretes hormone
estrogen.
4. Seminal vesicle and Prostate glands
i.
Produce ejaculatory fluid
which helps the sperm in transport and provides nutrition.
5. Uterus
i.
It accommodates a growing
foetus.
ii.
It push the baby during
labour.
3. Give scientific reason: Hormones secreted by the endocrine glands are present everywhere in the
body.
i.
Endocrine glands do not
have ducts to store or transport their secretions called hormones.
ii.
The hormones are directly
released into the blood stream and reach concerned body parts through blood.
iii.
Hence, hormones secreted by
the endocrine glands are present everywhere in the body.
4 . Explain the process of translocation in plants.
Ans.
i.
Transport of nutrients from
leaves to other parts of the plant is called translocation.
ii.
It takes place through
phloem in upward as well as downward direction.
iii.
This process needs energy
which is obtained from ATP.
iv.
When food materials like
sucrose are transferred to phloem tissue, using ATP, the concentration of water
molecules decreases in that area.
v.
This results in the
movement of water into the cells due to osmosis.
vi.
The increased contents
within the cells exert a high amount of pressure on their wall.
vii. This pressure moves the food materials to the adjacent cells with low
pressure.
viii. This allows the phloem to move material according to the plant’s needs.
5. How are
fats digested in the human body?
i.
Liver, the largest gland in
the body secretes bile juice which is stored in the gall bladder.
ii.
Whenever food enters the small
intestine, the gall bladder releases bile into it through a duct.
iii.
Bile makes the food
alkaline and breaks the large fat globules into smaller ones, this increases
the enzyme action.
iv.
Pancreas secretes digestive
juice. It has digestive enzymes like lipase which help to break down fats.
v.
Various intestinal juices
are also secreted by the walls of the small intestine to complete the digestion
process of converting fats into fatty acids.
6. Write short notes on Eutrophication
i.
The enrichment
of water bodies by inorganic plant nutrients like nitrate, phosphate occurring
either naturally or due to human activity is Eutrophication.
ii.
The process of
eutrophication takes place due to introduction of nutrients and chemicals
through discharge of domestic sewage, industrial effluents and fertilizers from
agricultural fields.
iii.
These promote
excessive growth of phytoplankton and algae. When algae die, decomposition of
organic substance use oxygen.
iv.
This results in depletion of oxygen in water. The bloom of algae blocks
penetration of oxygen, light and heat into the water body. As a result most of
the organisms die below the surface of the water.
8. Attempt the following (any
1) (5 marks.)
1. Explain the structure and function of a nephron.
Ans.
i.
The basic
filtration unit in the kidney is a cluster of thin walled blood capillaries
called as nephron.
ii.
Each
nephron has a cup shaped thin walled upper end called Bowman’s capsule which
contains a bundle of blood capillaries called glomerulus.
iii. When blood containing urea enters the glomerulus it gets filtered
through glomerular capillaries.
iv.
The
selectively permeable wall of the Bowman’s capsule allows the water molecules
and small molecules of the other substances to pass through them and forms
glomerular filtrate.
v.
The
blood, free from these materials is taken to the heart through the renal vein.
vi.
The
glomerular filtrate collected in the Bowman’s capsule further passes through
the nephron tubule where reabsorption of water and useful molecules take place.
vii. The remaining fluid containing the waste forms the urine which
eventually enters a long tube called the ureter.
viii. It is further stored in the urinary bladder and from there it is thrown
out through the urethra.
2 The
plants are kept in dark before determining the factors essential for
photosynthesis.
i.
When plants
perform photosynthesis, they produce carbohydrates. These carbohydrates are
used for their growth and energy.
ii.
The unutilized
carbohydrates are stored in the form of starch.
iii.
While
performing experiments on photosynthesis, it is necessary that this stored
starch is completely used up.
iv.
When the plant
is kept in dark, it utilizes this stored starch and becomes destarched.
v.
The factors
essential for photosynthesis such as carbon dioxide, sunlight and chlorophyll
can be studied with such destarched plant. Thus, the plants are kept in dark
before determining the factors essential for photosynthesis.
