Karnataka SSLC Science Model Question Paper 4 with Answers

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Karnataka State Syllabus SSLC Science Model Question Paper 4 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.
Significant role of stomata in transporation is to
A) create upward pressure
B) absorb carbon dioxide
C) release oxygen
D) perform transpiration continuously
Answer:
B) absorb carbon dioxide

Question 2.
Hydrogen gas is not liberated when a metal reacts with concentrated nitric acid because nitric acid
A) does not contain hydrgen atoms
B) oxidises itself
C) oxidises hydrogen to form water
D) is a strong reducing agent and gains hydrogen
Answer:
C) oxidises hydrogen to form water

Question 3.
Observe the following figure. We can understand that
Answer:

A) there is a uniform magnetic field around the solenoid
B) the magnetic field is same at all points inside the solenoid
C) solenoid is kept in a strong magnetic field
D) solenoid is experiencing mechanical force
Answer:
B) the magnetic field is same at all points inside the solenoid

Question 4.
In a power station coal is burnt to heat water to produce steam which further runs the turbine to generate electricity. This power station is a
A) Thermal power plant because coal is burnt
B) Hydro power plant because water is heated
C) Nuclear power plant because turbine runs
D) Bio gas power plant because coal is , used
Answer:
A) Thermal power plant because coal is burnt

Question 5.
A response that does not happen in plants due to their growth is
A) Bending of shoot towards light
B) Penetration of roots in deep soil
C) Folding of leaves when touched
D) Climbing tendrils of a creeper
Answer:
A) Bending of shoot towards light

Question 6.
In the environment, materials causing bio-magnification
A) get recycled quickly
B) decompose only in soil
C) remain as permanent residues
D) are stored in less amount in trophic levels
Answer:
C) remain as permanent residues

Question 7.
Ferrous sulphate crystals are taken in a test tube and heated; the correct statement related to this chemical reaction is
A) This is a photolytic decomposition reaction, and white coloured soild ferric oxide is formed
B) This is a thermal decomposition and green coloured fumes of ferric oxide is formed
C) This is a thermal decomposition . reaction and brown coloured fumes of ferric oxide is formed
D) This is a thermal decomposition reaction and brown coloured solid ferric oxide is formed
Answer:
D) This is a thermal decomposition reaction and brown coloured solid ferric oxide is formed

Question 8.
If one hydrogen atom of propane is replaced by a ketone group, then the molecular formula of the compound obtained is
A) C₄H₈O
B) C₃H₈O
C) C₃H₆O₂
D) C₄H₁₀O
Answer:
A) C₄H₈O

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

Question 9.
Complete this diagram by connecting two resistors R₁ & R₂ in series between A and B, also connecting two resistors R₃ & R₄ in parallel between C & D.
Answer:

Question 10.
What is esterification reaction?
Answer:
When an alcohol is treated with carboxylic acid in the presence of H₂SO₄ sweet smelling compound is formed which is called ester. The reaction is known as esterification reaction.
CH₃COOH + CH₃CH₂COOH → CH₃COOCH₂CH₃

Question 11.
Give scientific reason: “The magnetic field produced by a current carrying conductor increases as the number of turns in the coil increases”.
Answer:
According to law of electromagnetic induction, if current is passed through a conductor then magnetic field is produced around the conductor, if the number of turns in a coil are increased then the magnetic field of conductor also increases.

Question 12.
What similarity is observed in the structures of ‘A’ and ‘B’ with respect to their function?
Answer:

Oesophagus, we breath through this tube and this is the start of the digestive track.

Question 13.
A student connects a water heater to a 5A electric circuit. Is this correct? Give suitable reason to your answer.
Answer:
No, this is not correct. Water heater consumes large amount of energy. Connection with a low energy circuit can cause short circuit and overloading.

Question 14.
Use of CFC free refrigerators is considered as eco friendly. Why?
Answer:
This is because chloro fluoro carbon coming out from air conditioner and refrigerator has led to the depletion of ozone layer which protects us from UV rays which can cause many harmful diseases like skin cancer, loss of eyesight etc.

Question 15.
Write the products obtained when sodium oxide reacts with hydrochloric acid.
Answer:
As a strong base, sodium oxide reacts with hydrochloric acid to give sodium chloride solution and water.
Metal oxide + Acid → Salt + Water
Na₂O + 2HCl → 2NaCl + H₂O

Question 16.
Does the chemical reaction take place when zinc is added to ferrous sulphate solution? Justify your answer.
Answer:
Zn + FeSO₄ → ZnSO₄ + Fe
Zinc displaces iron from its sulphate solution as it is more reactive than iron.

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

Question 17.
Draw the diagram showing longitudinal section of a flower and label the part where pollination takes place.
Answer:

Question 18.
Explain the cleansing action of soaps.
Answer:
The dirt present on clothes is organic in nature and insoluble in water. Therefore, it cannot be removed by only washing with water. When soap is dissolved in water, its hydrophobic ends attach themselves in micelle formation and trap the dirt at the centre of the cluster. These micelles remains suspended in the water. Hence the dirt particles are easily washed away by water.

Explain the method of converting ethanol into ethanoic acid with the help of chemical equation.
Answer:
Oxidation of ethanol using acidified potassium dichromate gives ethanal in first step which on further oxidation by same oxidising agents gives ethanoic acid.

Question 19.
Draw the diagram of the arrangement of apparatus to show the action of steam on a metal and label the part where hydrogen is collected.
Answer:

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

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

Question 21.
“We need to look for alternative sources of energy”. Justify this statement scientifically.
Answer:
Fossil fuels which are traditionally used by human beings everywhere as an energy sources are non – renawable sources of energy. These sources of energy are limited and will disappear after some time. They are being consumed at a large rate. Therefore we should conserve the energy sources. Hence, we should look for alternate sources of energy.

Question 22.
Write the events occurring during photosynthesis.
Answer:
The three events that occur during the process of photosynthesis are :

Absorption of light energy by chlorophyll.
Conversion of light energy to chemical energy and splitting of water molecules into hydrogen and oxygen.
Reduction of carbon dioxide to carbohydrates.

Role of stomata : These help in the gaseous exchange between the plant and its atmosphere. Thus it assists in supply of carbondioxide essential for photosynthesis.

Question 23.
Explain the formation of covalent bond taking the example of methane and write the electron dot structure of methane.
Answer:
Carbon has four valence electrons. To achieve stability, it should follow the octet rule i.e, it should have 8 electrons in its valence shell. Hydrogen has 1 electron in its valence shell and should have 2 electrons in its valence shell to achieve stability. Thus, C shares each of its electrons with one hydrogen covalently to form CH₄ and achieve a stable form.

Question 24.
In the following circuit, which device can be connected in place of AB to increase or decrease the brightness of the bulb? Give reason for your answer.

A Resistor of resistance can be connected in place of AB to increase or decrease the brightness of the bulb. If the resistor is connected in parallel the current will be divided across all of them. But if the resistors are connected in series the current will be the same in all of them. The bulb with the lower resistance will conduct more current and therefore have a higher power dissipation and brightness.

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

Question 25.
Draw the ray diagram showing the image formation by a convex lens, when the object is kept between principal focus and optic centre. With the help of the diagram mention the nature of the image formed.
Answer:

The nature of the image is virtual and erect.

Question 26.
The reaction between lead nitrate and potassium iodide solutions is an example for what types of chemical reaction? Explain. Write the balanced chemical equation for this reaction.
Answer:
On mixing, two colourless solutions of lead nitrate and potassium iodide yellow precipitate is formed.

This is an example for a chemical reaction (double displacement) in which formation of precipitate is observed.

Question 27.
a) An object is kept between centre of curvature and principal focus of a concave mirror. Write the nature of the image formed.
Answer:

Real and inverted

b) Define focal length of a convex mirror. Write the relationship between focal length and radius of curvature of a convex mirror.
Answer:

The distance between the pole and the principal focus of a convex mirror is called the focal length of a convex mirror.
The relationship between focal length and radius of curvature of a convex mirror.
The radius of curvature is found to be equal to twice the focal length. R = 2f
This implies that the principal focus of a spherical mirror lies between length and centre of curvature,

a) Give any two examples for refraction of light in daily life. State the laws of refraction of light.
Answer:

Lemon kept in water in a glass tumbler.
A pencil partly immersed in water in a glass tumbler.

Laws of refraction of light

The incident 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 for the light of a given colour and for the given pair of media. This law is also called as Snell’s law of refraction.

\(\frac{\sin i}{\sin r}\) = Constant

b) The power of a lens is -2.5 D. Which type of lens is this?
Answer:
A concave lens has a negative focal length. Hence it is a concave lens.

Question 28.
In the modern periodic table, ‘A’ and ‘B’ are two elements belonging to first and seventeenth group respectively and both of them belong to the third period. Write their electronic configuration. Which of them is a metal? Why? Write the chemical formula of the compound obtained when these two elements react with each other.
Answer:
The two elements belongs to first and seventeenth group and third period is ‘A’ – Sodium (Na) and ‘B’ – Chlorine (Cl)
Na : 2, 8, 1
Cl: 2, 8,7

A(Sodium) will be the metal, because it has a single electron in its outer shell, which readily donates, creating a positively charged ion the Na+ cation.
Na⁺ + Cl^– → Nacl
When sodium reacts with chlorine to get sodium chloride.

\(_{6}^{12} \mathrm{C}\) and \(_{6}^{14} \mathrm{C}\) are two elements. Do both these elements get different positions in modern periodic table? Explain your answer. Identify the period and group to which they belong in the modern periodic table with suitable reason.
Answer:
No, \(_{6}^{12} \mathrm{C}\) and \(_{6}^{14} \mathrm{C}\) will be placed in same slot (position). The modem periodic table is based on atomic number, not on atomic mass. Since, both C -12 and C -14 have some atomic number, hence they are placed in same slot.

Question 29.
Observe the following chemical reactions
i) Fe₂O₃ + 2Al → 2Fe + Al₂O₃
ii) ZnO + C → Zn + CO
iii) Fe₂O₃ + 3C → 2Fe + CO
iv) Al₂O₃ + 3C → 2Al + 3CO
Which of the above reaction is wrong? How is the metal’present in the wrong equation extracted? Which of the above reaction can be used to join the broken parts of the machines. Why?
Answer:
Wrong reaction is (iv)
It is extracted by electrolysis (i) is used to join broken parts
∵ It is exothermic. Fe is in liquid state.

Question 30.
How is the end product of nutrition glucose breaks down among all the organisms under the conditions given below.
i) In the presence of atmospheric oxygen.
ii) In the absence of atmospheric oxygen
iii) in muscle cells due to lack of oxygen
Answer:
i) Carbon dioxide + water + energy
ii) Ethanol + carbon dioxide + energy
iii) Lactic acid + energy

Explain the methods of
i) Oxygen supply to the cells
ii) Release of carbondioxide to the atmopshere from the cells during the process of transportation in humans.
Answer:
i) 97% of oxygen is taken in the form of oxy-hemoglobin by hemoglobin pigment present in RBC of the blood from lungs to various parts and 3% of oxygen is transported in dissolved form in blood plasma.
ii) As carbon dioxide is more soluble in water than oxygen, it is mostly transported in the dissolved form in blood plasma.

Question 31.
Draw the diagram showing longitudinal section of human brain and label the following parts.
i) Part of hind brain that controls involuntary functions.
ii) The part that interprets sensory information.
Answer:

Question 32.
An electric motor is taken out from a toy car. How do you convert this motor into a small electric generator? Compare the function of electric generator with the phenomenon of electromagnetic induction.
Answer:
To convert an electric motor taken out from the toy car into a small electric generator we can follow these steps :

Take the electric motor from the toy car out of the vehicle.
Now connect some rotator cuff or anything so that the crank shaft can be rotated about its axis.
Now connect an LED bulb or any small bulb with the input points of the electric motor.

Now go on rotating the crankshaft. The electricity will be generated from the motor as the motor will now start acting as Dynamo.

The phenomenon which the motor is undergoing is termed as reverse electromagnetic induction in which the magnet is in the stationary position and the conductor rotates resulting in energy generation.
However, in electromagnetic induction the magnet moves and the conductor remains stationary.

Question 33.
Which ancient systems of water harvesting can be rejuvenated? What is the major advantage of these methods?
Answer:
Kattar, ponds, tals, tanks, surang arms pynes and ahars are some of the ancient water harvesting methods.

We can store more amount of water. This water is used for agricultural purpose and also we can generate electricity.
It provides moisture for vegetation over a wide area.
It is protected from contamination of human and animal waste.
It does not provide breeding grounds for mosquitoes like stagnant water collected in ponds.

Conscious usage of natural resources nowadays is inevitable. Why? Give reasons for you answer.
Answer:
The human population is increasing at a tremendous rate due to improvement in health care, the demand for all resources is increasing at an exponential rate. The proper management can ensure that the natural resources are used judiciously so that they fulfill the needs of present generation and also last for the generation to come. The proper management can ensure equitable distribution of natural resources so that all the people can benefit from the development of these resources.

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

Question 34.
Two black female mice are crossed with a brown male. Later female I produces 9 black and 7 brown offsprings, female II produced 57 black off springs during first filial generation. Then
i) What inference can you make ‘ concerning inheritance of black and brown coloured mice?
ii) With the help of phenotype given, find out what are the genotypes of parents?
Answer:
i) Inference regarding the inheritance of black and brown colour. Since the black colour genes are dominant over brown colour genes, only black coloured offsprings appear in the first filial generation, (in case of female 2).
ii) Since both black and brown offsprings are obtained when female 1 is crossed with a brown male (bb), its genotype would be Bb (heterozygous).
Female 2 will have genotype BB (homozygous).

Question 35.
a) What is Tyndall effect? Give two examples for Tyndall effect.
Answer:
The scattering of light by the particles in a colloidal medium is called Tyndall effect. Examples :

Sunlight passing through a dense forest.
Focusing a beam of red light in milk.
Passing a blue light to a dark room.

b) What is the meaning of power of accommodation of eye? How does this help us to see objects at different distances?
Answer:
The ability of eye to focus both near and distant objects, by adjusting the focal length is called power of accommodation of the eye.

When the ciliary muscles are releaxed, the, eye lens becomes thin, the focal length increases and the distant objects are clearly visible to the eyes. To see the near by objects clearly, the ciliary muscles contract making the eye lens thicken. Thus the focal length of the eye lens decrease and the near by objects become visible to the eyes.
Hence the human eye lens is able to adjust its focal length to view both distant objects.

Question 36.
a) Name the gas released at anode during chloro – alkali process and mention the uses of this gas.
Answer:
Chlorine gas is released at anode during chloro – alkali process.
Uses :

It is used in water treatment.
Manufacture of PVC.
Used as disinfectants and pesticides.
Used in swimming pools, CFC’s etc.

b) Which gas is released when sodium carbonate reacts with hydrochloric acid? How do you test this gas? Write the word equation for this reaction.
Answer:
Carbon dioxide (CO₂) gas is evolved when sodium carbonate reacts with hydrochloric acid. When the gas is passed through lime water it turns milky (showing that it is carbon dioxide) due to the formation of insoluble calcium carbonate.
Metal carbonate / Metal hydrogen carbonate + Acid → Salt + Carbondioxide + Water.

a) What happens if too much of acid is produced in the stomach? What is the remedy for this situation?
Answer:
If too much of acid is produced in the stomach it causes hyper acidity (Irritation and pain).
To get rid of this pain we have to use bases called antacids. It neutralises excess of acid and gives relief from pain caused by hyper acidity.

b) What is water of crystallization? How is plaster of paris prepared? Write any two uses of plaster of paris.
Answer:
The fixed number of water molecules present in one formula unit of a crystaline salt is called water of crystallisation.
Plaster of paris is prepared by heating gypsum to a temeprature of 100°C.
The following reaction takes place :

It is used to prepare chalks:
It is used to make casts and moulds.

Question 37.
a) Explain any two practical applications of heating effect of electric current.
The heating effect of electric current is used in the following applications.

Electric bulb : In an electric bulb, the filament of bulb gives light because of heating effect of electricity. The filament of bulb is generally made of tungsten metal, having melting point equal to 3380°C.
Electric iron : The element of electric iron is made of alloys having high melting point. Electric heater and rey – x on the same mechanism.

b) An electric bulb is connected to a 220 V generator. If the current drawn by the bulb is 0.5 A, then calculate the power of the bulb.
Answer:
Given V = 220, I = 0.50 A, P = ?
P = VI
= 220 V × 0.50 A
= 110 J/S
= 110 w

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

Question 38.
How are general growth and sexual maturation different from each other? Which are the symptoms observed in sexually matured females? When a matured female receives male sex cells due to sexual contact what changes will happen in her uterus?
Answer:
General growth is the growth of the human body such as increase in height, weight, change in shape and size. Sexual maturation refers to the changes that the human body undergoes at puberty like change of voice in males, breast development in females, menstruation in female, growth of hair in public region etc.

Increase in breast size.
Broadening of hips.
Appearance of hair under the armpits and in the genital area.
Beginning of menstrual cycle (uterus and ovary enlarge; ovary starts releasing egg)
Pimples on skin appear due to secretion of oil from the skin.

Once the zygote is implanted in the uterine wall, several changes takes place in the uterus. Uterus prepares itself to receive and nature the growing embryo. The uterine lining thickens and is richly supplied with blood to give support and nourishment to the growing embryo.