Karnataka SSLC Science Model Question Paper 3 with Answers

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Karnataka State Syllabus SSLC Science Model Question Paper 3 with Answers

Time: 3 Hours
Max Marks: 80

I. Four alternatives are provided for each of the following questions or incomplete statements. Choose the most appropriate alternative and write with its alphabet. ( 8 × 1 = 8 )

Question 1.
The power of lens is -4.0 D. What is the nature of the lens
A) plane
B) Concave
C) Plano-convex
D) convex
Answer:
B) Concave

Question 2.
By constructing Khadin check – dams in level terrains.
A) underground water level increases
B) underground water level decrease
C) vegetation in the nearby areas are destroyed due to excess moisture
D) underground water gets polluted
Answer:
A) underground water level increases

Question 3.
When the gases sulphurdioxide and hydrogen sulphide mix in the presence of water, the reaction SO₂ + 2H₂S → 2H₂O + 3S occur. Here hydrogen sulphide is acting as
A) an oxidising agent
B) a reducing agent
C) a dehydrating agent
D) a catalyst
Answer:
B) a reducing agent

Question 4.
What is the condition of an electromagnetic induction
A) There must be a relative motion between the coil of wire and galvanometer
B) There must be a relative motion between the galvanometer and a magnet
C) There must be a relative motion between gahario meter and generator
D) There must be a relative motion between the coil of wire and a magnet
Answer:
D) There must be a relative motion between the coil of wire and a magnet

Question 5.
The salts which make water hard are
A) calcium and magnesium sulphates
B) calcium and magnesium chlorides
C) calcium and magnesium bicarbonates
D) any of the above
Answer:
D) any of the above

Question 6.
Food cans are coated with tin and not with zinc because
A) zinc is costlier than tin
B) zinc has a higher melting point than tin
C) zinc is more reactive than tin
D) zinc is less reactive than tin
Answer:
C) zinc is more reactive than tin

Question 7.
A human hormone reducing blood flow to the digestive systems and skin during stress is
A) Thyroxin
B) Adernaline
C) Growth hormone
D) Insulin
Answer:
B) Adernaline

Question 8.
A cross between a tall plant (TT) and short pea plant (tt) resulted in progeny that were all tall plants because
A) Tallness is the dominant trait
B) Shortness is the dominant trait
C) Tallness is the recessive trait
D) Height of pea plant is not governed by gene ‘T’ or ‘t’
Answer:
A) Tallness is the dominant trait

II. Answer the following questions ( 8 × 1 = 8 )

Question 9.
What is the role of inhalation and exhalation?
Answer:
Diaphragm changes its shape during inhalation and exhalation, increases and decreases volume of thoracic cavity respectively. This causes entry and expulsion of air from lungs.

Question 10.
A student has difficulty reading the blackboard while sitting in the last row. What could be the defect the child is suffering from? How can it be corrected.
Answer:
The student is suffering from myopia or short sightdness. The defect can be corrected by the use of concave lens of suitable power.

Question 11.
Name the phenomenon associated with the use of (i) CFC (ii) DDT
Answer:
i) Ozone depletion
ii) Bio-magnification

Question 12.
Name the gas usually liberated when a dilute acid reacts with a metal. What happens when a burning candle is brought near this gas?
Answer:
H gas is liberated. It burns with pop sound when burning candle is brought near the gas.

Question 13.
Which endocrine gland is called master gland? Why?
Answer:
Pituitary gland is considered as master endocrine gland. It is said because it controls almost all other endocrine glands.

Question 14.
An alternating current has frequency of 50 Hz. How many times it has changed its direction in one second.
Answer:
100 times, 50 Hz frequency means AC generator completes 50 cycles in 1 second.

Question 15.
Mention the mode of reproduction used by
(a) Amoeba
(b) Planaria
Answer:
a) Amoeba is binary fission
b) Planaria is regeneration

Question 16.
Why is the reaction between methane and chlorine considered a substituion reaction.
Answer:
It is because Cl atoms substitutes H atoms of methane to form chloromethane and hydrogen chloride.

III. Answer the following questions ( 8 × 2 = 16 )

Question 17.
Compute the heat generated which transferring 96000 coulomb of charge in one hour through a potential difference 50 V.
Answer:
According to Joule’s law of heating the amount of heat produced is given by
H = Vt
Where V = 50 V

and t = 1 hour = 60 × 60 sec
So H = 50 × \(\frac{80}{30}\) × 60 × 60
= 4800000 J
= 4.8 × 10⁶ J

Question 18.
Draw the diagram of the apparatus used in the electrolysis of water.
Answer:

Question 19.
Write the difference between metals and non-metals on the basis of chemical properties.
Answer:
Metals:

• Oxides of metal are generally basic in nature.
• The compounds of metal are mostly ionic in nature.
• Metals acts as reducing agents as their atoms loose electrons.

Non metals:

• Oxides of non – metals are mostly acidic in nature.
• Compounds of non – metals are mostly covalent although there are many exceptions.
• Non – metals are oxidizing agents as their atoms accept electrons.
  Ex : Cl + e^Θ → Cl^Θ

OR

State two reasons for the following facts
i) Sulphur is a non – metal
Answer:
a) Poor conductor of heat and electricity
b) S + O₂ → SO₂
SO₂ +H₂O → H₂SO₃
Sulphurdioxide is acidic oxide.

ii) Magnesium is a metal
Answer:
a) Good conductor of heat and electricity
b) 2Mg + O₂ → 2MgO
Mgo + H₂O → Mg(OH)₂
Magnesium oxide is basic in nature.

Question 20.
Draw the ray diagram showing the recombination of the spectrum of white light.
Answer:

Question 21.
Draw the diagram of an electric generator.
Answer:

Question 22.
Name the hormones responsible for the following
i) Excess production causes gigantism
ii) Causes changes in the body during emergency.
iii) Induces wilting of leaves
iv) Target site is heart muscles, diaphragm and skin.
Answer:
i) Growth hormone
ii) Adrenaline
iii) Abscisic acid
iv) Oxytocin

Question 23.
How do Mendel’s experiments show that traits are inherited independently?
Answer:
Mendel crossed pure breeding tall plants having round seeds with pure breeding shorts plant with wrinkled seeds to prevent speciation. In their case, plants having wrinkled seeds. The plants of F₁ – Yielded plants with character of tall round seeded, 3 tall wrinkled seeded, 3 short round seeded and one short wrinkled seeded. Tall wrinkled seeded and combination which can develop only when the traits are inherited independently.

Question 24.
What is a homologus series? Explain with an example.
Answer:
A homologus series is a series of carbon compounds that have different number of carbon atoms but contain the same functional group. For example, methane, ethane, propane, butane etc, are all part of the alkane homologus series. The general formula of this series in
C_n H_2n+2
Methane : CH₃CH₄
Propane : CH₃ CH₂ CH₃
Butane : CH₃ CH₂ CH₂ CH₃ It can be noticed that there is a difference of CH₂ unit between each successive compounds.

OR

What are isomers? Give example.
Answer:
Compound with identical molecular formula but different structures are called structural isomers.

IV. Answer the following questions ( 9 × 3 = 27 )

Question 25.
Out of two elements A and B with mass number 2 and 235 respectively. Which one is suitable for making.
a) A nuclear reactor
b) A hydrogen bomb
Name the nuclear reaction involved in each case, write one difference between the two types of nuclear reactions.
Answer:
a) For a nuclear reactor – element ‘ B’ with mass number 235 is suitable as a fuel in nuclear reactor.
b) For a hydrogen bomb – element “A’ with mass number 2 is suitable for making the hydrogen bomb.
The nuclear reaction involved in
a) Nuclear reactor is nuclear fission reaction.
b) Nuclear bomb is nuclear fusion reaction.

Difference between fission and fusion.
Fusion reaction releases such greater energy with non – radioactive products than the energy released in fission reaction with radio – active products.

Question 26.
A coil of insulated copper wire connected to a galvanometer. What will happen if a bar magnet is
(i) pushed into the coil
(ii) withdrawn from inside the coil
(iii) held stationary inside the coil.
Answer:
i) An electric current is induced in the coil and the galvanometer shows a deflection.
ii) An electric current is induced in the coil but in opposite direction. The galvanometer shows a deflection but in reverse direction.
iii) No current is induced in the coil. The galvanometer shows no deflection,

Question 27.
Draw a diagram of human brain label the following parts.
i) Hypothallamus
ii) Cerebellum
Answer:

Question 28.
Name the three common defects of vision. What are their causes? Name the type of lens used to correct each of them.
Answer:
i) Myopia:
Cause: Elongation of eyeball.
Types of lens used for correction, concave lens of suitable power.

ii) Hypermetropia:
Cause: Shrinking of eyeball
Types of lens used for correction : Convex
lens of suitable power.

iii) Prerbyopia:
Cause: Weakening of ciliary muscles.
Type of lens used for correction : Bifocal lens.

OR

The far point of a myopic person is 80 cm in front of the eye. What is the nature and power of the lens required to correct the problem.
Answer:
The person is suffering from an eye defect called myopia. In this defect, the image is formed in front of the retina. Hence a concave lens is used to correct this defect of vision.
Object distance, u – infinity – ∞
Image distance, v = -8cm, Focal length = f
According to the lens formula

A concave lens of power -1.25 D is required by the person to correct his defect.

Question 29.
Draw the diagram of arrangement of apparatus used to show the reaction of Zinc granules with dilute sulphuric acid and testing hydrogen gas by burning label the following parts.
i) Soap solution ii) Delivery tube
Answer:

Question 30.
Balance the following chemical equation and identify the type of chemical reaction.

Answer:
a) It is a combination reaction.
b) It is a thermal decomposition reaction.
c) It is a combination reaction.

OR

What does one mean by exothermic and endothermic reaction? Give example.
Answer:
Exothermic reaction : Those reactions in which heat is evolved during the reaction are called exothermic reation.
Ex : Burning of coal.

Endothermic reaction : Those reactions in which heat is absorbed during the reaction are called enothermie reactions.
Ex : Decomposition of lime stone

Question 31.
Distinguish between homologus organs and analogus organs. In which catagory would you place wings of a bird and wings of a bat? Justify your answer giving a suitable reason.
Answer:
Homologus organs:

• They have same basic structural design
• They perform different functions.
• Their appearances are’ different.

Analogous organs:

• They have different basic structural design.
• They perform similar functions.
• They have similar appearance.

Wings of bird and wings of a bat are analogous organs as they have different basic structural design but have similar appearance and perform similar functions.

Question 32.
What is fertilization? Distinguish between external fertilisation and internal fertilisation.
Answer:
Fertilisation is defined as the fusion of a male gamete (sperm) with a female gamete (an ovum or egg) to form a zygote during sexual reproduction.

External fertilisation :

• The fusion of male gamete (sperm) and female gamete (ovum) occur outside the body.
• Both individuals discharge their gametes outside the body.
• Development occurs outside the body.
  Ex : frog.

Internal fertilisation :

• The fusion of gamates occurs inside the body.
• Only the male discharge sperm into female genital tract.
• Development occurs inside the body.
  Ex: Humans, cattle etc.

OR

Explain how sexual production gives rise to more viable variation than asexual reproduction. How does this affect the evolution of those organism that reproduce sexually.
Answer:
Sexual reproduction cause more viable variation due to the following reasons:

• Error in copying of DNA, which are not highly significant.
• Random segregation of paternal and maternal chromosomes at the time of gamete formation.
• Exchange of genetic material between homologous chromosomes during formation of garnets.
• Accumulation of variations occured due to sexual reproduction over generation after generation of selection by nature created wide diversity.

In case of sexual reproduction, only the very small changes due to inaccuracies in DNA copying pass on to the progency. Thus off-springs of a sexual reproduction are more or less genetically similar to their parents so it can be concluded that evolution in sexually reproducing organisms proceeds at a faster pace than in asexually reproducing organisms.

Question 33.
What is meant by water table? Why is it important?
Answer:
Water table : The level of water under the ground is called water table.
Advantages of underground water are:

• Instead of evaporation, the stored underground water recharges the wells by spreading out.
• It also provides moisture for vegetation over a wide area.
• It remains protected from contamination from animal and human wastes.
• It does not provide breeding ground for mosquitoes.

V. Answer the following questions. ( 4 × 4 = 16 )

Question 34.
a) What are groups and period in the periodic table?
b) Two elements M and N belong to group I and II respectively and are in the same period of the periodic table. How do the following properties of M and N vary?
1) Sizes of their atoms
2) Their metallic characters.
3) Their valencies informing oxides.
4) Molecular formula of their chlorides.
Answer:
a) The vertical columns in the periodic table are called group. The horizontal rows in the periodic table are called periods.
b) 1. M and N belong to the same period but I and II. Therefore N will be smaller than M as atomic size is decreasing from left to right.
2. M is more metallic than N. Metallic character goes on decreasing from left to right as tendency to lose electrons decreases due to decrease in atomic size.
3. Their valencies are 1 and 2 respectively in forming oxides.
Valency goes on increasing first and then increases.
4. MCl, NCl₂ are molecular formulae of their chlorides.

OR

Explain why the following statements are not correct?
i) All groups contain both metals and non metals.
Answer:
All groups do not contain both metals and non metals. Group I and II contain only metals.

ii) In group I, reactivity decreases with increase in atomic number.
Answer:
In group I, reactivity increases with increase in atomic number. This is because as the size of the atoms increases, the valence shell electrons can be easily removed.

iii) Elements in a period become more metallic with increasing atomic number.
Answer:
The metallic character decreases in a period with increase in atomic number. This is because across the period, the size of the atom decreases and the valence shell electron are held more tightly.

iv) Atoms of elements in the same group have the same number of electrons.
Answer:
In a neutral atom the number of electrons is equal to the number of protons. In a group the atomic number as we move down.

Question 35.
a) Write two points of difference between electric energy and electric power.
Answer:
Electric energy :
i) The work done or energy supplied by the source in maintaining the flow of electric current is called electrical energy. It appeare in the form of heat given by
H = vIt = \(\frac{v^{2} t}{R}\) = I² Rt
ii) It is equal to the product of power and time. E = P × t
iii) Its SI unit is joule (J)
1 J = 1W × 1S

Electric power :
i) The time rate at which electric energy is consumed or disipated by an electrical device is called electric power and is given by
P = vI = \(\frac{\mathrm{v}^{2}}{\mathrm{R}}\) = I²R
ii) It is equal to rate of doing work by an energy source.
P = \(\frac{W}{t}\)
iii) Its SI unit is Watt (W)
1 W = 1 JS^-1

b) An electric bulb of 200 Ω draws a current of 1 ampere. Calculate the power of the bulb the potential different at its ends and the energy in KWh consumed burning it for 5h.
Answer:
Power of the bulb
P = I²R = (1)² × 200
P = 200 W
Energy consumed by bulb in 5h in burning.
= Power × Time
= 200 × 5
= 1000 wh = 1 Kwh.

Question 36.
a) A, B and C are 3 elements which undergo chemical reaction according to following equations.
a) A₂O3 + 2B → B₂O₃ + 2A
b) 3CSO₄ + 2B → B₂(SO₄)₃ + 3C
c) 3CO + 2A → A₂SO₃ + 3C
Answer the following :
i) Which element is most reactive?
ii) Which element is least reactive?
b) Why is ZnO called amphoteric oxide?
Name another amphoteric oxide,
Answer:
a) i) Most reactive element is B as it has
replaced both A and C from their compounds.
ii) Element C is least reactive as it has been replaced both by A and B

b) Zinc oxide (Zno) is called amphoteric oxide as it behaves both as acidic oxide and basic oxide.

Alluminium oxide (Al₂O₃) is another amphoteric oxide.

Question 37.
Explain the process of nutrition in Amoeba.
Answer:
Amoeba is an important protozoa found in fresh water. If feeds on microscopic plants and animals present in water. The mode of nutrition in amoeba is holozoic and the process of obtaining food by amoeba is called phagocytosis. The different processes involved in the nutrition of amoeba are :

1) Ingestion :
Ingestion is the process of taking food in the body. Amoeba is a unicellular animal, so it doesn’t have a mouth for ingestion of food. Amoeba ingests the food by encircling it by forming pseudopodia, when the food is completely encircled the food is engulfed in the form of a bag called food vacuole.

2) Digestion :
Digestion is the process of breaking the large and insoluble molecules in to small and water soluble molecules. In amoeba several digestive enzymes react on the food present in the food vacuoles and break it down into simple and soluble moleculer.

3) Absorption :
The food digested by digestive enzyme .is then obsorbed in the cytoplasm by the process of diffusion. While the undigested food remains in the food vacuole. If a large amount of food is obsorbed by amoeba, the excess is stored in the cytoplasm in the form of glycogen and lipids.

4) Assimilation :
During this step the food obsorbed by the cytoplasm is used to obtain energy, growth and repair. This process of utilizing obsorbed food for obtaining energy, repair and growth is called assimilation.

5) Egestion :
When, a sufficient amount of undigested food gets collected in the food vacuole it is thrown out of the body by rupturing cell membranes. The process of removal of undigested food from the body is called Egestion.

VI. Answer the following question. ( 1 × 5 = 5 )

Question 38.
State the laws of refraction. What is the meaning of the refractive index of crown glass is 1.52. Define the power of lens. What is the meaning of ‘The power of a lens is 1 diaptor’. If the power of a lens is -2.0 D, then what type of lens is that? When an object is kept at infinity from this type of lens, what is the size of the image formed?
Answer:
Laws of refraction of light are :
The indident ray, the refracted ray and the normal to the interface of two transparent media at the point of incidence, all lie in the same plane.

The ratio of sine of angle of incidence to the sine of angle of refraction is a constant.
\(\frac{\sin i}{\sin r}\) = Constant
This means that the ratio of the speed of light in air and the speed of light in crown glass is equal to 1.52.
The ability of a lens to converge or diverge the ray of light after refraction is called power (p) of lens.
It is defined as the reciprocal of the focal length i.e., p = \(\frac{1}{f}\)

S.I unit of power of a lens is dipotre. A lens of focal length 100 cm has a power of 1 dipotre i.e, 1 dioptre = 1m^-1
If the power of a lens is -2.0 D then the type of lens is concave lens.
The size of the image in the lens is highly diminished, point sized.