Key Answer
MGSS
KSEEB - SSLC SCIENCE MODELS QUESTION PAPER – 5
Sub: Science Sub. Code: 83E Time: 3.15 Hour Max Marks: 80
PART A: PHYSICS
I. Four
alternatives are given for each of the following questions/incomplete
statements. Choose the correct alternative and write the complete answer along
with its letter of alphabet. 4 x 1 = 4
1. The source of energy in nuclear power reactor is:
A. Nuclear fission reaction B. Exothermic chemical reaction
C. Nuclear fusion reaction D. controlled nuclear fission
chain reaction
Ans: A. Nuclear fission reaction
2. Which of the following is NOT a
property of magnetic lines?
A. Magnetic field lines are dense near
poles
B. Magnetic field lines are closed loops
C. Magnetic field lines intersect each
other
D. Magnetic field lines emerge from
north pole and merge at the south pole
Ans: C. Magnetic field lines intersect each other
3. The work done in moving a charge of
2C across two points having a potential difference 12V is :
A. 24 J B. 6 J C. 14 J D. 10 J
Ans: A. 24 J
4. The correct way of using electrical
appliances in domestic electric circuit is
A. Connecting electrical appliances in
series
B. using an electrical appliance of 880
W power in 5A electric circuit
C. Connecting main fuse to electrical
appliances in parallel
D. using an electrical appliance of 2 KW
power in 5A electric circuit
Ans: C. Connecting main fuse to electrical appliances in parallel
II.
Answer the following questions.
2 x 1 = 2
5.
State Fleming’s left hand rule.
Ans:
According to Fleming’s left hand rule, the centre finger gives the direction of current and middle finger points in the direction of magnetic field then the thumb points towards the direction of the force or motion of the conductor.
6.
Name the lens that always produces erect, diminished and virtual image.
Ans:
A concave lens always produces erect, diminished and virtual image.
III.
Answer the following questions. 2
x 2 = 4
7.
Draw the diagram of the electric circuit used to study Ohm’s law and label
voltmeter.
Ans:
8.
‘Bio-mass is a renewable source of energy’. Justify this statement with
suitable reasons.
Ans:
Biomass is considered a renewable energy source because its inherent energy comes from the sun and
because it can regrow in a relatively short time. Trees take in carbon dioxide
from the atmosphere and convert it into biomass and when they die, it is released back into the
atmosphere.
IV.
Answer the following questions. 3
x 3 = 9
9.
Draw the ray diagram to show the formation of image by a convex lens when the
object is placed beyond 2F1 . Mention the position and nature of the image with
help of the diagram. (F1 : Principal focus of the convex lens)
Ans:
10.
What is electric current? Mention the use of battery in an electric circuit.
Write the factors on which the resistance of a conductor depends.
Ans:
Electric Current is the rate of flow of electrons in a conductor.
The role of a battery (or cell) in an electric circuit is to supply energy to the circuit by doing work upon the charge to move it from the low energy terminal to the high energy terminal.
The resistance of the conductor depends on the following factors:
- The temperature of
the conductor.
- The cross-sectional
area of the conductor.
- Length of the conductor.
- Nature of the
material of the conductor.
11.
An electric lamp whose resistance is 20 Ω and a conductor of 4 Ω resistance are
connected in series to a 6V battery. Find the current through the circuit and
the potential difference across the electrical lamp and conductor.
Ans:
The resistance of the
electric lamp R1 = 20 Ω.
The resistance of the
conductor connected in series R2 = 4 Ω.
The total resistance in the
circuit
R = R1 + R2
R = 20 Ω + 4 Ω = 24 Ω
the total potential difference across the two terminals of the battery V = 6 V.
By Ohm's law, the current
through the circuit is given by
I = V/R
= 6 V/24
= 0.25 A
On applying Ohm's law to the
electric lamp and resistor separately, we get potential difference across the
electric lamp
V1 = 20 Ω
× 0.25 A = 5 V
and that across the
conductor
V2 =
4 Ω × 0.25 A = 1 V
OR
A
copper wire has diameter 0.5 mm and resistivity of 1.6 x 10−8 Ω m. What should
be the lenght of this wire to make its resistance 10 Ω.
Ans:
Area of cross-section of the wire, A =π
(d/2) 2
Diameter= 0.5 mm = 0.0005 m
Resistance, R = 10 Ω
We know that
∴
length of the wire = 122.72m
V.
Answer the following question.
1 x 4 = 4
12.
State the laws of refraction of light. Different media have different
refractive index. Why? ‘The refractive index of glass is 1.5’. What is the
meaning of this statement?
Ans:
The incident ray refracted ray, and the normal to the interface of two media at the point of
incidence all lie on the same plane.
The ratio of the sine of the angle of incidence to the sine of the angle of refraction is a
constant. This is also known as Snell's law of refraction.
Light propagates with different speeds in different media. The value of the refractive index for a given pair of media depends upon the speed of light in the two media.
Refractive index of glass is 1.5 . This means that
the speed of light in glass is 1.5 times slower than the speed
of light in vacuum.
OR
A
concave lens of focal length 15 cm forms an image 10 cm from the lens. How far
is the object placed from the lens? Find the magnification produced by the
lens. With the help of this mention the nature of the image.
Ans:
f = -15 cm
v = -10 cm
Lens formula: 1/v – 1/u =1/f
1/-10 – 1/u = 1/-15
1/u = - (1/10) + 1/15
1/u = -2/60
u = -30 cm
Object is at 30 cm from the
concave lens (on left side).
The nature of the image
virtual, erect and diminished.
VI.
Answer the following question. 1 x 5 = 5
13.
Explain Faraday’s experiment of magnet and coil. What factors can be observed
when the magnet is replaced by a coil carrying current? What are the
conclusions that can be drawn by you from these experiments? State
electromagnetic induction with the help of this experiment.
Ans:
Experiment
1: In this experiment, Faraday
connected a coil to a galvanometer, As the bar
magnet is shifted towards the coil, the pointer in the galvanometer gets
deflected, thus indicating the presence of current in the coil. This shows that
only the relative motion between the magnet and the coil are responsible for
the generation of current in the coil.
Experiment
2: In
the second experiment, Faraday replaced the bar magnet by a second
current-carrying coil that was connected to a battery. As we move the second
coil towards the primary coil, the pointer in the galvanometer undergoes deflection; all these results show that
the system in the second case is analogous to the system in the first
experiment.
Experiment
3:
He placed two stationary
coils and connected one of them to the galvanometer and the other to a battery,
through a push-button. As the button was pressed, the galvanometer in the other
coil showed a deflection, indicating the presence of current in that coil.
This proved that the relative motion between
the coils was not really necessary for the current in the primary to be
generated.
Conclusion:
An
emf is induced in the circuit changes with the amount of magnetic flux (number
of magnetic lines per unit area) changes and magnitude of the induced emf in
the circuit is equal to the time rate of change of magnetic flux through the
circuit.
Electromagnetic Induction or Induction is
a process in which a conductor is put in a particular position and magnetic
field keeps varying or magnetic field is stationary and a conductor is moving.
This produces a Voltage or EMF (Electromotive Force) across the electrical
conductor.
PART: B CHEMISTRY
VII.
Four alternatives are given for each of the following questions/incomplete
statements. Choose the correct alternative and write the complete answer along
with its letter of alphabet. 2 x 1 = 2
A.
Methanal B. Methanone C. Ethanal D. Methanoic acid
Ans: A. Methanal
15.
Observe the following stages of extraction of a metal from its ore. Sulphide
ore → …………. → Reduction → Purification The process that has to be done in the
empty space is
A.
Electrolysis B. Calcination C. Roasting D. Oxidation
Ans: C. Roasting
VIII.
Answer the following questions. 4
x 1 = 4
16.
What is a strong acid?
Ans:
Acids that
give high concentration of H+ ions on ionisation in aqueous
solution are said to be strong
acids
17.
State modern periodic law.
Ans:
Moseley gave the Modern Periodic Law which states that: Physical and
chemical properties of the elements are the periodic function of their atomic numbers.
18.
The metallic property of elements increases down the group in the modern
periodic table. Why?
Ans:
Metallic character increases
as you move down an element group in the periodic table. This is because
electrons become easier to lose as the atomic radius increases, where there is
less attraction between the nucleus and the valence electrons because of the
increased distance between them.
19.
What is substitution reaction?
Ans:
The reactions in which an
atom or group of atoms in a molecule is replaced or substituted by different
atoms or group of atoms are called substitution.
IX.
Answer the following questions. 3 x 2 = 6
20.
The compounds C2 H4 , C3 H6 , C4 H8 , C5 H10 are in homologous series. Why?
Write the general name and general formula for these carbon compounds.
Ans:
They have common difference of CH2 among each compounds.
They have similar chemical properties. They have same functional groups .
The general formula :- CnH2n
The common name is :- alkenes
21.
The atomic number of an element is 20. In which period of the modern periodic
table, could this element be placed? Why? How will you decide whether the
element is a metal or a non-metal?
Ans:
· The no. of shells present are 4 n therefore it belongs to period 4.
·
As the elements
placed towards the right-side or present in the s-block are metals, therefore this element is a metal.
22.
Why is a metal oxide called a basic
oxide? Name the products obtained when copper oxide reacts with dilute
hydrochloric acid.
Ans:
Metallic oxides are basic in nature because
they react with dilute acids to form salt and water.
copper oxide reacts with dilute HCl, it produces cuprous chloride(salt)
and water.
OR
The test tube ‘A’ contains distilled water,
test tube ‘B’ contains acidic solution and test tube ‘C’ contains basic
solution. How could these samples be identified using red litmus paper.
Ans:
The solution which turns red litmus to blue
contains a basic solution. The solution from the test tube which turns blue
litmus paper to red will be the acidic solution and solution of the test tube
which do not change either red or blue litmus paper contain water.
X.
Answer the following questions. 3 x 3 = 9
23.
Draw the diagram of the arrangement of the apparatus showing the reaction of
zinc granules with dilute sulphuric acid and testing hydrogen gas by burning.
Label the following parts :
(i) Zinc granules (ii) Delivery tube
Ans:
24. Explain the
properties of carbon due to which it forms large number of compounds.
Ans:
(i) Catenation: The self linking property of an element mainly
carbon atom through covalent bonds to form long straight, branched and rings of
different sizes are called Catenation.
This property is due to
·
The small size of the
carbon atom.
·
The great strength of
the carbon-carbon bond.
(ii)
Tetravalent Nature: Carbon
has valency of four. It is capable of bonding with four other atoms of carbon
or some other heteroatoms with single covalent bond as well as double or triple
bond.
OR
Explain
the cleaning action of soaps.
Ans:
Most of the dirt is oily in
nature and oil does not dissolve in water. The molecule of soap constitutes
sodium or potassium salts of long-chain carboxylic acids. In the case of soaps,
the carbon chain dissolves in oil and the ionic end dissolves in water. Thus,
the soap molecules form structures called micelles. In
micelles, one end is towards the oil droplet and the other end which is the
ionic faces outside. Therefore, it forms an emulsion in water and helps in
dissolving the dirt when we wash our clothes.
25.
Draw the diagram of the apparatus used in the electrolytic refining of copper.
Label the following parts.
(i) Cathode (ii) Anode mud
Ans:
XI.
Answer the following question. 1
x 4 = 4
26.
a) Explain the formation of the ionic compound magnesium chloride with the help
of electron dot structure.
Ans:
·
During the formation of
the ionic bond, a single magnesium atom loses two electrons. On the other hand,
two chlorine atoms gain one electron each.
·
Hence, magnesium atom
becomes cation (positively charged ion) and each chlorine atoms become anions
(negatively charged ion).
b)
Write the balanced chemical equation for the reaction of aluminium metal with
steam.
Ans:
2Al+3H2O→Al2O3+3H2
When
steam is passed over aluminium , aluminium reacts with steam to form aluminium
oxide and hydrogen gas.
PART: C BIOLOGY
XII. Four alternatives are given for each of the
following questions/incomplete statements. Choose the correct alternative and
write the complete answer along with its letter of alphabet.
2 x 1 =
2
27. The materials that change slowly
their form and nature are
A. Used tea leaves B. Peels of vegetables
C. Waste papers D. Plants fibers
Ans: C. Waste papers
28. The pattern of response in the roots
of plants is
A. Directional and negatively
phototropic
B. Positively phototropic and negatively
geotropic
C. Non-directional and positively
geotropic
D. Growth dependent and positively
hydrotropic
Ans: C.
Non-directional and positively geotropic
XIII. Answer the following questions. 2
x 1 = 2
29. Mention the reason for the depletion
of ozone layer.
Ans:
Ozone layer depletion is
caused due to the release of chemical compounds containing gaseous
bromine or chlorine from industries or other human activities.”
30. Name any two ancient systems that
were practiced to harvest rain water.
Ans:
khadin, ponds, kuls, nadis….
XIV. Answer the following questions. 3
x 2 = 6
31. How is oxygen rich blood from the
lungs supplied to all the cells in the human body?
Ans:
The right ventricle pumps the blood from the right atrium into the lungs to pick up oxygen and remove carbon dioxide. The left atrium receives blood from the lungs. This blood is rich in oxygen. The left ventricle pumps the blood from the left atrium out to the body, supplying all organs with oxygen-rich blood.
OR
How are the products of photosynthesis
from the leaves get transported to all other parts of the plant?
Ans:
The food which is prepared by the process of
photosynthesis in the leaves of a plant has
to be transported to other parts like
stem, roots, branches etc. Therefore this food is transported
to other parts of the plant through a kind of tubes called phloem.
Oxygen, a by-product of photosynthesis,
and water vapor exit the leaf.
32. The people who live in and around
the forest are said to be the stakeholders of the forest. Why? Explain.
Ans:
Local people around Forest are referred to as ''stkeholder''because Locals are depend on forest produce. Everyone uses forest resources in one form or the other.
The stakeholders of forest resources include:
- People who
live around the forest areas and depend upon the forest resources for
sustenance.
- The
Government Forest Department, which owns the forest land
- The
industrialists who use forest products for various industrial purposes.
- The
enthusiasts for the conservation of wildlife and natur
33. Draw the diagram showing the
germination of pollen on stigma and label `female germ cell’.
Ans:
XV. Answer the following questions. 3 x 3 = 9
34. How do genes control the
expression of ‘tall’ or ‘short’ traits in plants?
Ans:
Genes
are the section of DNA that carry the chromosome and determine the
characteristics of an organism.
Suppose,
a plant species has a gene for tallness will give instructions to the plant
cells to generate many plant-growth hormones due to which the plant will grow
tall. On the other hand, if the plant has the gene for shortness then less
plant-growth hormones will be produced, due to which the plant will not grow
much and remain a dwarf plant.
Or
‘Acquired traits of an individual
organism during its life time cannot direct the evolution’. Explain this
statement with an illustration.
Ans:
Acquired traits are due to changes in the lifestyle, injury, loss of body parts, disuse of some body parts. These are the traits which occur in the somatic cells.These changes occur in the non-reproductive tissues, these cannot be passed into the DNA of the germ cells. hence acquired characters are not inherited.
35.
In female reproductive system,
(i)
How does an egg from the ovary reach uterus and develops into foetus?
Ans:
A pregnancy starts with
fertilization, when a woman's egg joins
with a man's sperm. Fertilization usually takes place in a fallopian tube that links
an ovary to the uterus. If the fertilized egg successfully travels down the
fallopian tube and implants in the uterus, an embryo starts growing.
(ii)
What are the changes that occur in the uterus for the development of the
foetus?
Ans:
During pregnancy, the lining of your uterus thickens and its blood vessels enlarge to provide nourishment to the fetus. As pregnancy progresses, your uterus expands to make room for the fetus. By the time your baby is born, your uterus will have expanded to many times its normal size.
Or
In sexual reproduction,
(i) How does the re-establishment of DNA
amount occur in the new generation?
Ans:
When
the gametes fuse during fertilization, the resulting new generation organism gets one
pair of chromosome (Haploid) from each parent and thus the chromosome becomes
diploid. Thus, the full number of chromosomes is re-established and the
specific chromosome number of a species is maintained.
(ii) How is the amount of variations
increase among the individuals of each of the population?
Ans:
Gene
duplication, mutation, or other processes can produce new genes and alleles
and increase genetic variation. New genetic variation can be created within
generations in a population, so a population with rapid
reproduction rates will probably have high genetic variation.
36.
Draw the diagram showing the structure of nephron. Label the following parts.
(i) Bowman’s capsule (ii) Collecting duct
Ans:
XVI.
Answer the following questions. 2 x 4 = 8
37.
a) How do the ‘homologous characteristics’ in different organisms help to
identify the evolutionary relationships?
Ans:
organisms that share similar physical
features and genomes tend to be more closely related than those that do not. Such features that
overlap both morphologically (in form) and genetically are referred to as homologous structures; they stem
from developmental similarities that are based on evolution.
b) How does Mendel’s ‘monohybrid cross’ experiment clarify that, `the traits of an organism independently inherit to the progenies?
Ans:
Genes
located on different chromosomes will be inherited independently of each
other. Mendel observed
that, when peas with more than one trait were
crossed, the progeny did not
always match the parents. This is because different traits are inherited independently –
this is the principle of independent assortmen
38.
a) Name the mineral required for the production of thyroxine hormone. What is
the use of this hormone to our body?
Ans:
·
The thyroid gland
uses iodine from food to make thyroid hormones
·
Controls
general metabolism and growth in the body.
b)
What are involuntary actions? Name the parts of the human brain that control
voluntary and involuntary actions.
Ans:
·
Involuntary action is
the set of muscle movement which do not require thinking. But it is controlled
by brain for example beating of heart beat.
·
The part of the brain
that controls involuntary functions is medulla oblongata. The part of the brain that controls voluntary actions is cerebrum.
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