Key Answer
MGSS
KSEEB - SSLC SCIENCE MODELS QUESTION PAPER – 1(2021-22)
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. 2x1=2
1. The diameter of the reflecting surface of spherical mirror is
A) Optical Centre B) Centre of Curvature C) Aperture D) Principal axis
Ans: C) Aperture
2. An electric motor takes 5A from a 220V electric source. The power of the motor is
A) 1100W B) 44W C) 225W D) 440W
Ans: A) 1100W
II Answer the following questions. 3x1=3
3. If the focal length of a spherical mirror is 15cm. Find the radius of curvature ?
Ans: R = 2f, R = 2×15, R = 30cm
4. Mention any two disadvantages of fossil fuels.
Ans:
- Fossil fuels are not renewable energy sources
- Fossil fuels pollute the environment.
5. What is an electric circuit ?
Ans: A continuous and closed path of an electric current is called an electric circuit.
III Answer the following questions. 3x2=6
6. How does overloading and short-circuit occur in an electric circuit? Explain. What is the function of a fuse during this situation ?
Ans: The over usage of electricity in a circuit more than its limit is called overload. In other words, the rising of electric load in a circuit is called overload. The live wire and the neutral wire come into direct contact is called short circuit. The function of fuse in these situations is to cut off the rising load.
7. Draw the schematic diagram of a biogas plant.
Ans:
8 An electric lamp whose resistance is 40Ω and conductor of 8Ω resistance are connected in series to 12V battery in an electric circuit. Calculate the total resistance of the circuit and the current flowing through the circuit.
Ans:
In series combination,
IV Answer the following questions. 3x3=9
9. Draw the ray diagram of image formed when the object is kept beyond
2F1
of the convex lens. With the help of the diagram, mention the position
and nature of the image formed. (F1 : principal focus of the lens)
Ans:
Image position : between F2 and 2F2
Nature: Real, Inverted and Diminished
OR
Draw the ray diagram when of image formed the object is kept beyond C
of the concave mirror. With the help of the diagram mention the position
and nature of the image formed. (C : Centre of curvature of mirror).
Ans:
Image position: Between C and F
Nature of image: Real, Inverted and diminished
10. What is electric potential difference? What is the SI unit of potential
difference ? Name the device used to measure the potential difference.
Ans:
The potential difference between two points in an electric circuit. is defined as the work done to Move unit Electric Charge from one Point to another in an electric circuit.
SI unit of potential difference is volt.
device used to measure the potential difference is voltmeter.
11. An object is kept at a distance of 30cm from a diverging lens of focal length 15cm. At what distance the image is formed from the lens? Find the magnification of the image.
Ans:u = -30cm.
V Answer the following questions 2x4=8
12. Explain Faraday’s experiment of magnet and coil. State “electromagnetic
induction” with the help of this experiment
Ans:
- Take a wire, a bar magnet and a galvanometer
- Move the magnet towards the coil of wire.
- The galvanometer moves to indicate a current in the wire.
- When the direction of the magnet is reversed, the current reverses (indicated by the galvanometer needle swaying in the opposite direction)
- When the speed of movement of the magnet changes, the galvanometer deflects faster.
- Moving a magnet towards a coil induces a current in the coil is called electromagnetic induction.
OR
State the Fleming’s right hand rule. How can we increase the amount
of electric current produced in the electric generator ? Write any two
differences between electric generator and electric motor?
Ans: “Hold the right-hand forefinger, middle finger and the thumb at right angles to each other. If the forefinger represents the direction of the magnetic field, the thumb points in the direction of motion or applied force, then the middle finger points in the direction of the induced current.”
- increasing the rate of rotation.
- increasing the strength of the magnetic field.
- increasing the number of turns on the coil.
Electric Motor:
- An electric motor is a machine that converts electrical energy to mechanical energy.
- Electric motor follows Fleming’s left-hand rule.
Electric generator:
- An electric generator is a machine that converts mechanical energy to electrical energy.
- Electric generator follows Fleming’s right-hand rule
13. a) List the uses of Convex mirror and Concave mirror.
b) Define principal focus and radius of curvature of a convex mirror.
Ans: a)
Convex mirror
- used as rear view mirror in vehicle
- used in street light
concave mirror
- used in torches and vehicle headlight
- used as shaving mirror
b) principal focus: A number of rays parallel to the principal axis after reflection the reflected ray appear to meet at a point on the principal axis. This is called principal focus of convex mirror.
radius of curvature: is the distance between center of the curvature and pole of mirror.
PART - B
CHEMISTRY
VI Four alternatives are given for each of the following questions / incomplete
statements. Choose the correct alternative and write to the complete
answer along with its letter of alphabet. 2x1=2
14. As the pH value of a solution increases.
A) number of H+
ions increases B) number of OH–
ions increases
C) number of OH–
ions decreases D) equal number of H+
and OH–
ions
Ans: B) number of OH– ions increases
15. The amphoteric oxide among the following is
A) Potassium oxide B) Sodium oxide C) Calcium oxide D) Zinc oxide
Ans: D) Zinc oxide
VII Answer the following question. 1x1=1
16. State Newlands’ law of octaves.
Ans: Newland's law of octaves states that when elements are arranged in the order of their increasing atomic mass, the properties of every eighth element are the same as the first.
VIII Answer the following questions. 2x2=4
17. Draw the diagram of the arrangement of apparatus to show the electrolysis
of water and label the ‘graphite rod’.
18. Write the molecular formula and two uses of each of the following
compounds:
a) Washing soda
b) Bleaching powder
Ans: Washing soda
- used in glass, soap and paper industries.
- it is used in removing permanent hardness of water.
bleaching powder
- it is used as oxidising agent in many in many chemical industries
- it is used to make drinking water free
OR
Name the two gases liberated in Chlor-alkali process. Write one use of
each.
Ans: Chlorine gas:
- used in water teatment, swimming pool, pestiside
hydrogen gas:
- used as fuel
IX Answer the following questions. 3x3=9
19. Draw the diagram of arrangement of the apparatus to show the reaction
of zinc granules with dilute sulphuric acid and testing hydrogen gas by
burning. Label the following parts.
i) zinc granules ii) soap solution
Ans:
Ans: The reaction of lead with copper chloride solution is an example of displacement reaction
Because of lead is more reactive than copper. so, lead displace the copper from its compound
Pb(s) + CuCl2(aq) -----> PbCl2(aq) + Cu(s)
OR
Write the balanced chemical equations for the following reactions and
identify the exothermic and endothermic reaction.
i) heating of ferrous sulphate crystals.
ii) calcium oxide reacts with water.
Ans: i) heating of ferrous sulphate crystals is an endothermic reaction
Heating
2FeSO4(s) -----------> Fe2O3(s)
+ SO2(g) + SO3(s)
ii) Reaction of calcium oxide with water is an exothermic reaction
CaO(s) + H2O(l) ---------> Ca(OH)2(aq)
+ Heat
21. The atomic numbers of two elements are 12 and 16 respectively. Do
you keep these two elements in the same period of the modern periodic
table? Justify your answer. Which one of these two elements is more
electropositive? Why?
Ans: The atomic number of elements 12 is Mg and 16 is S both elements are occurs in same period because Mg and S have valence electrons present in 3rd main shell.
Ans: The atomic number of elements 12 is Mg and 16 is S both elements are occurs in same period because Mg and S have valence electrons present in 3rd main shell.
element atomic number 12(Mg) is more electropositive than the atomic number of element 16(S) because atomic number 12(Mg) is a metal and atomic number 16(S) is a non-metal and elecropositivity decreases from left to right
X Answer the following question. 1x4=4
22. a) Ionic compounds in solid state do not conduct electricity, but in
molten state are good conductors of electricity. Why ?
b) Write the formation of magnesium chloride (MgCl2
) with the help of
electron dot structure.
Ans: a) In the solid state ionic compounds do not conduct electricity because movement of ions in the solid is not possible due to their rigid structure. In molten state, electrostatic forces of attraction between the oppositely charged ions are overcome due to the heat. thus the ions move freely and conduct electricity.
b)
The magnesium atom transfers its one electron to each chlorine atom to form an ionic bond.
XI Answer the following questions. 1x5=5
23. a) Write any two differences between saturated and unsaturated carbon
compounds.
b) Write the molecular formula and structural formula for the following
carbon compounds.
i) propanoic acid ii) cyclohexane iii) pentane
Ans: a)
| Saturated hydrocarbons | Unsaturated hydrocarbons |
| Saturated hydrocarbons are the compounds containing only single covalent bonds. These are also known as alkanes. | Unsaturated hydrocarbons are the straight chain compounds containing double or triple covalent bonds. |
| These compounds are less reactive. | These compounds are more reactive. |
| These compounds under go substitution reactions. | These compounds under go addition reactions. |
b) i) C2H5COOH ii) C6H12  |  |
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. 4x1=4
24. The plant hormone that causes wilting of leaves is
A) cytokinin B) auxin C) abscisic acid D) gibberellin
Ans: C) abscisic acid
25. The correct sequence of reproductive stages occur in flowering
plants is
A) gametes, zygote, embryo, seed. B) zygote, gametes, embryo, seed.
C) seed, embryo, zygote, gametes. D) gametes, embryo, zygote, seed.
Ans: A) gametes, zygote, embryo, seed.
26. The site of complete digestion of carbohydrates, proteins and fats is
A) large intestine B) stomach C) liver D) small intestine
Ans: D) small intestine
27. The unfertilized egg of human female contains
A) One ‘Y’ Chromosome B) One ‘X’ Chromosome
C) ‘XX’ Chromosomes D) ‘X’ and ‘Y’ Chromosomes
Ans: B) One ‘X’ Chromosome
XIII Answer the following questions. 4x1=4
28. The folding up of leaves of a sensitive plant (touch me not plant) on
touching with a finger is not a tropism. Why ?
Ans: The folding up of leaves in a sensitive plant on touching is not a tropism (like thigmotropism) because it is a non-directional movement, means the direction of movement of leaves does not depend on the direction of the stimulus (touch).
29. What are analogous organs ?
Ans: organs having different structure and similar function is called analogous organs.
30. What is the role of decomposer in an ecosystem?
Ans: they act as a cleansing agent of the environment by decomposing dead plants and animals into useful substances.
31. Why are traits acquired during its lifetime of an individual not inherited?
Ans: acquired traits are not inherited because these changes in non-reproductive tissues ( Somatic cells ) which cannot be passed on to the next progeny.
XIV Answer the following questions. 3x2=6
32. Draw the diagram showing the structure of nephron and label bowman’s
capsule.
Ans:
33. Write any two differences between biodegradable and non biodegradable
substances
Ans:
Biodegradable Substances | Non-biodegradable Substances |
They are considered safe for the environment | They are considered harmful to the environment |
Biodegradable substances are natural wastes | Non-biodegradable substances are synthetic wastes |
Biodegradable substances do not cause pollution | Non-biodegradable substances cause pollution |
OR
Write a grassland food chain and name the different tropic levels in it.
Ans: Gross--->Grosshoppers-->Frogs-->Snakes
Gross are the producers and represents the first trophic level
Gross hoppers are the primary consumers and represents the second trophic level
Frogs are the secondary consumers and represents the third trophic level
Snakes are the tertiary consumers and represents the fourth trophic level
34. “The flow of energy in an ecosystem is unidirectional” How ? Justify
Ans: once the energy utilized by the organisms in food chain can't be revert back to the sun. Similarly, the energy once used by carnivores can't be revert back to herbivores which means that the flow of energy in an ecosystem is unidirectional.
XV Answer the following questions. 3x3=9
35. Write the flowchart to show the breakdown of glucose by various pathways
in the cytoplasm of living organisms.
Ans:
OR
Explain the function of stomach in the human digestive system.
Ans: Stomach acts as a storage for the food and provides enough time to digest meals. The stomach also produces mucous, digestive enzymes and hydrochloric acid that maintains the process of digestion.
Mucous: It protecting the stomach lining and gastric pits from the acid.
Digestive enzymes: They are the group of enzymes which functions by breaking down complex substances into simpler substances.
Hydrochloric acid: It destroying harmful microorganisms present in the food particles.
36. Explain the human male reproductive system.
Ans: The male reproductive system includes the testes, scrotum, seminal vesicles, vas deferens, testicles (testes), and prostate gland and penis. All these organs work together to produce sperms, the male gamete, male sex hormones and other components of semen.
Scrotum: It is a sac of thick skin that protects and surrounds the testes. It also controls the temperature of the testes
Testes: A pair of testes are present in humans. it produce testosterone – a male sex hormone and sperms
The male accessory glands generate fluid that nourishes the sperm.
37. The tall pea plant bearing red colour flowers (TTRR) is crossed with dwarf
pea plant bearing white flowers (ttrr). Represents the result obtained in F2
generation of dihybrid cross with the help of checker board. Mention the
ratio of different plants obtained in F2
generation.
Ans:
OR
What is Speciation? Mention the factors could lead to the rise of a new
species.
Ans: Speciation is the process of formation of new species from existing populations
factors that lead to the rise of a new species
- Genetic drift.
- Natural selection.
- Genetic mutation.
- Geographical isolation.
- Reproductive isolation.
- Environmental factors on the isolated populations.
XVI Answer the following question. 1x4=4
38. Draw the diagram showing structure of human brain. Label the following
parts.
i) cerebrum ii) cerebellum
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