Karnataka SSLC Science Model Question Paper 2 with Answers

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Karnataka State Syllabus SSLC Science Model Question Paper 2 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.
Lack of oxygen in muscles often leads to cramps among cricketers. This results due to
A) Conversion of pyruvate to ethanol
B) Conversion of pyruvate to glucose
C) Conversion of pyruvate to lactic acid
D) Conversion of pyruvate to carbon dioxide and water
Answer:
C) Conversion of pyruvate to lactic acid

Question 2.
Observe the following chemical equations and identify the correct statement.
(i) CuSO₄ + Fe → FeSO₄ + Cu
(ii) 2AgNO₃ + Cu → Cu (NO₃)₂ + 2Ag
A) Copper is more reactive than Iron and Silver
B) Iron is less reactive than Copper and Silver
C) Copper is more reactive than Silver but less reactive than Iron
D) Silver is more reactive than Copper and Iron
Answer:
C) Copper is more reactive than Silver but less reactive than Iron

Question 3.
In an ecosystem, the 10% energy available for transfer from one trophic level to the next is in the form of
A) Heat energy
B) Light energy
C) Chemical energy
D) Mechanical energy
Answer:
C) Chemical energy

Question 4.
Which of the following is not an oxidising agent
A) oxygen
B) conc sulphuric acid
C) chlorine
D) hydrogen
Answer:
B) conc sulphuric acid

Question 5.
An antiseptic to sterilise wounds and syringes in hospitals
A) Propanol
B) Ethylalcohol
C) Butanol
D) Methanol
Answer:
B) Ethylalcohol

Question 6.
Which of the following correctly describes the magnetic field near a long straight wire?
A) The field consists of straight line perpendicular to the wire.
B) The field consists of straight lines parallel to the wire.
C) The field consists of radial lines originating from the wire.
D) The field consists of concentric circles centered on the wire.
Answer:
D) The field consists of concentric circles centered on the wire.

Question 7.
Most of the sources of energy we are represent stored solar energy. Which of the following is not ultimately derived from the sun’s energy
A) Geothermal energy
B) Wind energy
C) Fossil fuel
D) Biomass
Answer:
A) Geothermal energy

Question 8.
The growth, of tendrils in pea plants is due to :
A) Rapid cell divisions in the tendril in the region away from support
B) Rapid cell division in the tendril in the region of contact to the support.
C) The effect of light
D) The effect of gravity
Answer:
A) Rapid cell divisions in the tendril in the region away from support

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

Question 9.
What is neutralisation reaction?
Answer:
When an acid reacts’ with a base to form salt and water, it is called neutralisation reaction.

Question 10.
What do you mean by double circulation of blood?
Answer:
Blood passes through the heart twice for each cycle through the body. .

Question 11.
What do you understand by the term natural selection?
Answer:
According to theory of natural selection, nature selects fittest animal. Animals which are not fit are eliminated by nature itself.

Question 12.
Which one is having lesser resistance, a 60 W bulb or a 40 W bulb?
Answer:
Power (P) = \(\frac{V^{2}}{R}\)
∴R α \(\frac{1}{\mathrm{P}}\)
if v is constant.
Hence bulb of higher voltage will have less resistance. In other words, resistance of 60 W bulb is less than the resistance of 40W bulb.

Question 13.
What two characteristics are observed when dilute hydrochloric acid is added to zinc granules?
Answer:
The two characteristics observed are evolution of a gas and evolution of heat energy.

Question 14.
An organic compound burns with a sooty flame. Is it saturated or unsaturated compounds.
Answer:
It is an unsaturated compound because, it contains high carbon and low hydrogen and bums with sooty flame.

Question 15.
What is an armature?
Answer:
The soft iron core, on which the coil is wound plus the coils is called an armature.

Question 16.
What are the two general principles of energy flow?
Answer:

1. The flow of energy is unidirectional.
2. As the energy moves progressively through the various tropic levels, it is no longer available to the previous level.

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

Question 17.
How is caustic soda obtained? Mention its uses.
Answer:
Caustic Soda (NaOH) is manufactured by electrolysis of aqueous solution of sodium chloride (Brine). This method is called chloro alkali process.
2NaCl_(aq) + 2H₂O_(l) →2NaOH_(aq) + Cl₂ + H₂
Sodium hydroxide is used in making soaps and detergents, decreasing metals, paper making and artificial fibers like rayon.

Question 18.
Draw a diagram of testing the conductivity of a salt solution.
Answer:

Figure
Testing the conductivity of a salt solution

Question 19.
Energy transfer is said to be unidirectional where biochemical transfer is said to be cyclic? Why.
Answer:
The flow of energy is unidirectional because the energy lost as heat to the environment can’t be reutilized by plants for photosynthesis. Energy decrease at each tropic level (10% of previous level). Hence it can’t be reused again. Whereas biochemical transfer is cyclic because nutrients utilized by plants and animals are returned to environment after the death of organisms.

Question 20.
What is Myopia? Name the lens used to correct Myopia.
Answer:
Myopia (short sightedness) is the inability of an eye in viewing long distant objects.
The Myopia is corrected by using a concave tens which diverges and shifts the image to the retina.

OR

The far point of a’ myopic person is 150 cm in front of eye, calculate the focal length and the power of lens to enable see distant object clearly.
Answer:
Far point (v) = 150 cm

Question 21.
Draw the diagram of the electric circuit in which the esistors R₁, R₂ and R₃ are connected in series including ammeter and voltmeter and mark the direction of current.
Answer:

Question 22.
Draw the diagram of the structure of a nephron.
Answer:

Question 23.
How is Plaster of Paris prepared? What reaction takes place when it sets to a hard mass?
Answer:
Plaster of Paris is preapred by heating gypsum to a temeprature of 100°C. The following reaction takes place:

On mixing with water, it react to a hard mass to form gypsum again i.e, the reverse reaction takes place.

Question 24.
What is reproduction? What are its two types? Which one of the two confers new characteristics on the offsprings and how?
Answer:
Reproduction is the process of producing new individuals of the same species by existing organisms of a species, i.e, parents. Its two types are ; Sexual and Asexual reproduction Sexual reproduction confers new characteristics on the offsprings due to variation in DNA.

OR

How will an organism be benefited if it reproduces through spores?
Answer:

• Large number of spores are produced in one sporangium.
• Spores are distributed easily by air to far off places to avoid competition at one place.
• Spores are covered by thick walls to prevent dehydration under unfavorable conditions.

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

Question 25.
One day Suresh connected many house hold high power appliances having a current rating more than 6A to a multiplug of 6A rating when he was about to switch them on his elder sister shouted and asked him to remove the appliances from a single socket.
a) According to you, why she would not advice to connect multi high power, appliances on a single socket?
b) What would have happened if he switched them on.
c) What was the value shown by his sister.
Answer:
a) Connecting too many appliances to a single Socket can cause overloading.
b) A large amount of current would have flowed through the circuit beyond permissible value i.e, 6A. Due to over loading the wires of the circuit get heated which may also cause fire,
c) Knowledge application, concern for her brother, presence of mind.

Question 26.
Draw the ray diagrams for the image formation in a convex lens when an object is placed.
i) at focus F₁
ii) beyond 2F₁
Answer:

Question 27.
How can you as an individual contribute or make a different to the management of
a) Forests and wildlife
b) Water resources and
c) Coal and petroleum
Answer:
a) Forests and wildlife:

• Take part in community activities with focus on conserving forests and wildlife
• As a tourist follow all principles of conservation.
• Help organisation engaged in conservation of forests and wildlife.

b) Water resources:

• Save water in domestic use.
• Install a system for rainwater harvesting.

c) Coal and petroleum:

• Save electricity.
• Install electric gadgets that use less power
• Use public transport.

OR

a) What is Biomass.
Answer:
The material contained in the bodies of plants and animals is called biomass,

b) An environmentalist on visit to your school suggested the use of three R’s to save the environment. Explain what he meant by three R’s and how you would follow his advice at home.
Answer:
Three R’s to save the environment : We can reduce pressure on the environment by applying the maximum of reduce, recycle and reuse in our lives.

Reduce means to use less:

• By switching off unnecessary lights and fans to save electricity.
• By repairing leaky taps to save water.
• By not wasting food.
• Recycle means to collect plastic, paper glass and metal items and recycle these materials to make required things.
• In order to recycle, firstly segregation of waste is necessary so that materials that can be recycled are not dumped along with other wastes. Reuse means to use things again and again.
• The used envelope can be reversed and used again instead of being thrown away.
• The plastic bottles of food items like jam or pickle can be used for storing things in the kitchen.

Question 28.
Draw the diagram showing the structure of schematic sectional view of the human heart and label the following parts, i) Arota ii) Septum
Answer:

Question 29.
Define refractive index of a transparent medium. What is its unit? Which has a higher refractive index glass or water? The radius of curvature of a spherical mirror is 20 cm. What is its focal length.
Answer:
The ratio of the speed of light in the free space (c) to the speed of light in given medium (V) is called its refractive index.
n = \(\frac{C}{V}\)
It has no unit, glass has more refractive index than water.
Radius of curvature, R = 20cm
Radius of curvature of a spherical mirror = 2 x Focal length (f)
R = 2f
f = \(\frac{R}{2}=\frac{20}{2}\) = 10 cm
Hence, the focal length of the given spherical mirror is 10 cm.

OR

The magnification produced by a plane mirror is +1. What does this means. An object is placed at a distance of 10 cm from a convex mirror of focal length 15 cm. Find the position and nature of the image.
Answer:
The positive sign means image formed by a plane mirror is virtual and erect since the magnification is 1. It means that the size of the image is equal to the size of the object.

Focal length of convex mirror, f = + 15 cm.
Object distance, u = -10 cm
According to the mirror formula

The image is located at the distance 6 cm from the mirror on the other side of the mirror.
The positive sign and value less than 1 of the magnification indicates that the, image formed virtual and erect and diminished.

Question 30.
i) Who proposed Modern – periodic law?
Answer:
Henry Mosely proposed modern periodic law.

ii) How does the electronic configuration of an atom of an element relate to its position in the modern periodic table? Explain with one example.
Answer:
The position of elements depends upon number of valence electrons which depend up on electronic configuration. Those elements which have some valence electrons, occupy same group. Those elements which have one valence electron belong to group 1. Elements which have two valence electrons belong to group 2.

Period number is equal to the number of shells. Example, atomic number of Na is 11, So its electronic configuration is 2, 8, 1. As sodium has one valence electron in its valence shell, so it belongs to group 1. As sodium has 3 shells, it belongs to 3rd period.

OR

The position of three elements A,B and C in the periodic table are shown below

a) State whether A is non metal or metal
b) State whether C is more reactive or less reactive than A
c) Will C be larger or smaller in size than B
Answer:
a) Elements of group 17 have seven electrons in their respective valence shells and thus have a strong tendency to gain one or more electrons to complete their respective octets. Thus C which is an element of group 17 is a non – metal.

b) As we move down the group, the atomic size increase. Therefore, the force of attraction of the nucleus for the incoming electron decreases and hence the reactivity decreases down the group. Since the element C has larger atomic size than the element A, therefore, the element C is less reactive than the element A.

c) Element B and C belong to the same period, i.e, 5^th period. As we move from left to right in a period, the nuclear charge increases but the number of shells remains to be the same. Therefore, the size decreases from left to right. Thus, the atomic size of G is smaller than that of B.

Question 31.
a) What is a balanced chemical equation?
Answer:
An equation in which the number of atoms of each on the two side of an equation is equal is called a balanced chemical equation.

b) Write the balanced reactions for the following :
(i) Potassium Bromide + Barium iodide → Potassium iodide Barium Bromide.
Answer:
2KBr (aq) + BaI₂ (aq)→ 2KI (aq) + BaBr₂ (aq)

(ii) Zinc carbonate Zinc oxide + carbondioxide
Answer:
ZnCO₃(s) → ZnO(s) + CO₂(g)

Question 32.
a) Explain the formation of Na₂O by the transfer of electrons.
b) Name the constituent metals of bronze.
Answer:
a) Sodium has one electron in the outermost shell while oxygen has six. To complete its octet. Oxygen needs two more electrons. But to complete the octet, sodium loses one electron. In order to equalise the number of electrons lost and gained, two atoms of sodium combine with one atom of oxygen. The formation of Na,0 is shown below

b) Bronze is made up of copper and tin.

OR

Give reason for the following :
a) Metals are regarded as electropositive elements.
Answer:
Metals have a tendency to lose one or more electrons to form positive ions. Therefore, metals are called electro positive elements.

b) When a piece of copper metal is added to a solution of Zinc sulphate, no change take place, but the blue colour of copper sulphate fades away when a piece of zinc is placed in its solution.
Answer:
Copper is less reactive than Zinc. Therefore, if cannot displace Zinc from ZnSO₄ solution. But Zinc being more reactive than copper, it displaces copper from CuSO₄ solution. As a result the concentration of Cu²⁺ ions fall and blue colour fades.

c) Articles of aluminium do not corrode even though aluminium is an active metal.
Answer:
Aluminium being a reactive metal readily combines with oxygen to give a protective layer of Al₂O₃ AS a result further corrosion stops.

Question 33.
Mention the function of forebrain, cerebellum and medulla.
Answer:

• Forebrain : It is the major thinking part of the brain. Hypothalamus part of diencephalon in the fore brain controls hunger, thirst, fatigue, sleep, body temperature, sweating and emotions.
• Cerebellum: Precision of valuntary action such as walking in a straight line, riding a bicycle, picking up a pencil are possible because of cerebellum.
• Medulla : Involuntary action such as maintaining blood pressure, salivation, vomiting are controlled by the medulla of the hind brain.

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

Question 34.
a) Explain the terms :
i) Speciation
ii) Natural selection
Answer:
i) Speciation: Speciation is the evolution of reproduction isolation among once interbreeding population i.e, the development of one or more species from an existing species.
ii) Natural selection: Natural relationship in the process, according to Darwin, which bring about the evolution of new species of animals and parents.

b) List four factors which could lead to speciation.
Answer:
Four factors which can lead to speciation are :

1. Genetic drift : Over generation, genetic drift may accumulate which lead to speciation.
2. Natural selection: Natural selection which may give rise to speciation.
3. Severe DNA change
4. A variation may occur which does not allow sexual act between two groups.

OR

a) What factors could lead to the rise of a new species.
Answer:
Natural selection, genetic drift and acquisition of traits during the lift time of an individual can give rise to new species.

b) Only variations that can have an advantage to an individual organism will survive in a population. Do you agree with this statement why or why not.
Answer:
In species variations that offer survival advantage are naturally selected individuals adjust to their environment with the help of those selected are passed on to their progeny evolution of organisms occurs as a result of this natural selection.

However there can be some other variations which do not offer any survival advantage of some genes even if they are not important for survival.

This accidental change in the frequency of gene in small population is referred to as genetic drift. Thus genetic drift provides diversity without any survival advantage.

Question 35.
How can ethanol and ethanoic acid be differentiated on the basis of their physical and chemical properties?
Answer:
I. Physical properties:

1. Smell: Ethanoic acid has a pungent smell while ethanol has a pleasant smell.
2. Melting point : The melting point of ethanol is much lower (156 k) than that of ethanoic acid (290 k) In winter season ethanoic acid freezes to form glacier like crystal while ethanol remains as a liquid.
3. Boiling point: The boiling point of ethanoic acid is much higher (391)k than that of ethanol (351 k)
4. Action of litmus: Ethanol is a neutral compound and hence it neither turns blue litmus red, nor red litmus blue. In contrast ethanoic acid is acidic in nature and hence turns blue litmus red.

II. Chemical properties:

1. Action of sodium carbonate and sodium hydrogen carbonate: Ethanoic acid produce brisk effervesence due to the evolution of CO₂ gas from sodium carbonate or sodium hydrogen carbonate but ethanol does not.
2CH₃COOH +Na₂CO₃ → 2CH₃COONa + CO₂ + H₂O
CH₃ COOH + NaHCO₃ → CH₃ COOHNa + CO₂ + H₂O

2. Action of alkaline potassium permanaganate:- Ethanol discharges the pink colour of KMnO₄ but ethanoic acid does not.

Question 36.
What are the different method of contraception?
Answer:
Contraceptive method can be broadly divided into the following types :

• Natural method : It involves avoiding the chances of meeting of sperms and ovum. In this method, the sexual act is avoided from 10th to 17th of the menstrual cycle because during this period, ovulation is expected and therefore the chance of fertilization are very high.
• Barrier method : In this method, the fertilization of ovum and sperms is prevented with the help of barriers. Barriers are available for both males and females. Condoms are barriers made of thin rubber that are used to cover penis in male and vagina in females.
• Oral contraceptives : In this method tablets or drugs are taken orally. They contain small doses of Harmones that prevent the release of eggs and thus fertilization cannot occur.
• Implants and Surgical methods : Contraceptive devices such as the loop or copper – T are placed in utreus to prevent pregnancy. Some surgical methods can” also be used to block the gamete transfer to prevent the transfer of sperms known as vastectomy. Similarly, fallopian tubes of the female can be blocked so that egg will not reach the utreus known as tubectomy.

Question 37.
a) What is hypermetropia? What are the two causes of this defect of vision.
Answer:
Hypermetropia is the defect in which a person can see distance objects clearly but cannot see the nearby objects.
The two possible causes of this defect are :

1. Increase in the focal length of the eye lens.
2. Eyeball gets shortened.

b) What is the colour of the clear sky during day time. Give reason for it.
Answer:
When sunlight passes through the atmosphere having the molecules of air and other fine particles whose size is smaller than the wave length of visible light these molecules and particles scatter the blue colour more strongly than the other colours of spectrum as the wave length of blue colour is more. This scattered blue light enters our eye, so the colour of sky appears blue to us during day time.

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

Question 38.
What is the resistance of a conductor? Mention the factors on which the resistance of a conductor depend.
Answer:
Resistance of a conductor is the property of a conductor by virtue of which it opposes the flow of current through it.
The resistance of the conductor depends

• On its length
• On its area of cross section and
• On the nature of its materials.

b) An electric bulb of 200 Q 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
Power of the bulb, P = I²R = (l)² x 200
P = 200 W
Energy consumed by bulb in 5h in burning.
= Power x Time
= 200 x 5
= 1000 wh= 1 Kwh