MG SCHOOL EDUCATION: KSEEB - Science Model Question Paper

Key Answer

MGSS

KSEEB - SSLC SCIENCE MODEL QUESTION PAPER – 1

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. 3 x 1 = 3

1. The SI unit of electric charges is:

A. volt B. ampere C. coulomb D. joule

Ans: C. coulomb

2. The suitable focal length of the convex lens used as magnifying lens to read “Hallmark 916’’ written on ornaments is :

A. 12 cm B. 60 cm C. 100 cm D. 120 cm

Ans: A. 12 cm

3. The magnetic field lines inside a solenoid are in the form of parallel straight lines. The reason for this is, the magnetic field inside the solenoid is:

A. very high B. uniform C. zero D. produced by electricity

Ans: B. uniform

II. Answer the following questions. 2 x 1 = 2

4. If the radius of curvature of a lens is 30 cm, then what is its focal length?

Ans:

When radius of curvature , R = 30 cm

then , R = 2f or f = R / 2 or f = 30 /2 so, f = 15 cm

5. In the experiment of refraction through a glass slab, the angle of incidence should be less than 90°. Why?

Ans:

If the rays of light are incident upon the glass surface perpendicularly, or at 90 degree angle to the surface, the rays will pass through without changing direction. In this case, the angle of incidence and angle of refraction are always zero.

III. Answer the following questions. 3 x 2 = 6

6. Draw the ray diagram to show the formation of image by a convex lens when the object is kept between 2F1 and F1 . (F1 : Principal focus of the convex lens)

Ans:

7. The resistivity of two conductors ‘A’ and ‘B’ are 1.62 x 10−8 Ω m and 5.20 x 10−8 Ω m respectively. Which of them is used in :

(i) Transportation of electricity (ii) The making of heating coils? Why?

Ans:

(i) Conductor A

(ii) Conductor B because it's resistivity is more than Conductor A so it will resist more electricity.

8. Observe the following table. Complete the table using Ohm’s law :

Ans:

Ohm's law Formula = V = IR

Where

V = Potential Difference I = Electric Current R = Resistance

i) Given I = 2A V = 120V

To Find Resistance (R)

Formula V=IR 120V = 2A×(R) R = 120V/2A R = 60Ω

ii) Given I = 1.5A R = 60Ω

To Find Potential difference (V)

Formula V= IR V = 1.5×60 V = 90V

(iii) Given V = 60V R = 60Ω

To Find Current (I)

Formula V = IR 60V = I60Ω I = 60/60 I = 1A

IV. Answer the following questions. 3 x 3 = 9

9. Draw the diagram of an electric generator. Label the following parts.

(i) Carbon Brushes (ii) Rings

Ans:

10. Explain the experiment to find out the focal length of a convex lens. The focal length of a convex lens is 100 cm. Find its power.

Ans:

Given that,

Focal length f = 100 cm

We know that,

The power of the lens is the reciprocal of the focal length of the lens.

The power of the lens is

Here, P = power of the lens

f = focal length of the lens

Power =. 1 / focal length (in m)

P =. 1/ 1 m

P = 1 dioptre

An object is kept at a distance of 30 cm from a diverging lens of focal length 15 cm. At what distance the image is formed from the lens? Find the magnification of the image.

Ans:

A concave lens(diverging lens) always forms a virtual, erect image on the same side of the object.

u = -30cm. f = -15cm v=?

1/f= 1/v - 1/u

1/-15= 1/v - 1/-30

-1/v= 1/15 +1/30

-1/v= 2+1/30

-1/v= 3/30

v= -10cm.

magnification= v/u

m= -10/-30 m=0.34

+ ve sign shows that the image is virtual and erect. the image is one third of the object

11. Explain the advantages and disadvantages of solar cells.

Ans:

Advantages of Solar cells

Disadvantages of Solar cells

· Renewable source of energy

· Environment friendly

· Easy to maintain.

· Very useful in remote locations where there is a power crisis

· Initial setup cost is high.

V. Answer the following questions. 2 x 4 = 8

12. Explain the principle of working of simple electric motor. What is the role of split rings in an electric motor? How are commercial motors different from simple electric motor?

Ans:

· The principle of an electric motor is based on the current carrying conductor which produces magnetic field around it. A current carrying conductor is placed perpendicular to the magnetic field so that it experiences a force.

· In electric motors, the splittings acts as a commutator. The reversal of current also reverses the direction of force acting on the two arms AB and CD. The reversing of the current is repeated at each half rotation, giving rise to a continuous rotation of the coil and to the axle.

· In commercial motor an electromagnet is used in place of permanent magnet. Commercial motors have more number of turns of conducting wire in current carrying coil. Commercial motors have soft iron core on which the coil is wound.

Explain the following with reference to the magnetic field around a straight conductor carrying current.

(i) Tracing the pattern of magnetic field

(ii) Increasing the intensity of magnetic field

(iii) Reversing the direction of electric current.

Ans:

(i) Tracing the pattern of magnetic field

The two ways to trace the magnetic field of a bar magnet is by a compass and by iron filings in the compass needle method, the needle rotate freely and trace it. In another way, the iron filings make the magnetic path.

(ii) Increasing the intensity of magnetic field

The strength of the magnetic field around a conductor can be increased by increasing the current.

(iii) Reversing the direction of electric current.

When reverse the direction of the current in the wire, the north and south poles are also reversed. When reverse the current again, the north and south poles reverse again. In fact, each time the current is reversed, the north and south poles will exchange places.

13. a) State Ohm’s law. Mention the factors on which the resistance of a conductor depends.

Ans:

A law stating that electric current is proportional to voltage and inversely proportional to resistance.

Factors on which the resistance of a conductor depends are:

· Length of wire.

· Cross section area or thickness of wire.

· Nature of the material.

· Temperature

Resistance of wire is directly proportional to length and temperature and inversely proportional to cross section area.

b) State Joule’s law of heating and write the mathematical formula of this law.

Ans:

Joule's law of heating states that heat produced when a current of I flows in a wire of resistance R ohms for time t seconds is given by

H = I²Rt.

H =Heat

I =Current

R=Resistance of a conductor

T=Time taken

PART B: CHEMISTRY

VI. 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. 3 x 1 = 3

14. The gas liberated when an acid reacts with a metal is:

A. Hydrogen B. Chlorine C. Carbon dioxide D. Nitrogen dioxide

Ans: A. Hydrogen

15. The hydrocarbon that undergoes addition reaction among the following is :

A. C₂H₆ B. C₃ H₈ C. CH₄ D. C₃ H₆

Ans: D. C₃ H₆

16. In modern periodic table, as we move from left to right along the period, the atomic size of the elements.

A. increases B. does not change

C. decreases D. first increases and then decreases

Ans: C. decreases

VII. Answer the following questions. 3 x 1 = 3

17. Is it possible to test the hardness of water using detergents? Give reason for your answer.

Ans:

No, because detergent gives lather with hard and soft water both, while a soap gives lather with soft water only. Thus, it is not possible to check if water is hard by using a detergent.

18. in the modern periodic table, the elements of 17th group are Flourine, Chlorine, Bromine, Iodine respectively. Which element has the highest ability to receive electrons? Why

Ans:

Fluorine is more electronegative than other elements because fluorine is smaller and has its electrons closer to the positively charged nucleus. So that fluorine has more tendency to attract shared electrons to itself.

19. Ionic compounds have high melting points. Why?

Ans:

Because the ions are held together tightly by strong forces of attraction between the oppositely charged ions so, it takes a lot of energy to break all the bonds. As a result, ionic compounds have high melting and boiling points.

VIII. Answer the following questions. 3 x 2 = 6

20. Name the Ketone having four carbon atoms and write its structure.

Ans:

Butanone or Ethyl methyl ketone has four carbon atoms.

Explain combustion reaction of carbon compounds with an example.

Ans:

The complete combustion of carbon compounds in the air gives carbon dioxide water, heat and light.
CH₄(g) + 2O₂(g) → CO₂(g) + 2H₂O(l) + Heat and light

Saturated hydrocarbons burn with a blue flame in the presence of a sufficient supply of air or oxygen. In presence of limited supply of air, saturated hydrocarbon forms a sooty flame.

Unsaturated hydrocarbons burn with a yellow smoky flame.

21. Draw the diagram of the apparatus used to show that acid solution in water conducts electricity and label dilute hydrochloric acid

Ans:

22. The gas liberated when sodium carbonate reacts with dilute hydrochloric acid is passed through lime water, a white precipitate is formed. But when the same gas is passed through lime water in excess, precipitate is not visible. Why?

Ans:

When excess of carbon dioxide is passed through lime water, it makes milky colour of lime water disappear. This happens because of formation of calcium hydrogen carbonate. As calcium hydrogen carbonate is soluble in water, thus, the milky colour of solution mixture disappears.

IX. Answer the following questions. 3 x 3 = 9

23. Explain the limitations of Medeleev’s periodic table.

Ans:

Elements with large differences in properties were included in the same group.
No proper position could be given to the element hydrogen.
The increasing order of atomic mass was not strictly followed throughout. For example in cobalt and nickel & Tellurium and Indium.
As isotopes are atoms of the same element having different atomic masses, not given different positions while arranging them in the order of atomic mass.

Explain the limitations of Newlands’ law of Octaves.

Ans:

Law of Octaves only applicable upto calcium and after calcium every 8th did not possess properties similar to that of the first.
later on , several new elements were discovered, whose properties did not fit into the aw of octaves
Newlands'law of Octaves worked well with lighter elements only.

24. Write one difference between saturated carbon compounds and unsaturated carbon compounds. Carbon forms covalent bonds with other atoms but not ionic bonds. Why? Explain.

Ans:

Saturated Hydrocarbon	Unsaturated Hydrocarbon

Contain more hydrogen atoms than the corresponding unsaturated hydrocarbons.	Contain fewer hydrogens than the corresponding saturated hydrocarbon.
Examples include alkanes and cycloalkanes.	Examples include alkenes, alkynes, and aromatic hydrocarbons.
They have a relatively low chemical reactivity	They are more reactive than their saturated counterparts.
They generally burn with a blue flame	They generally burn with a sooty flame.

Carbon forms covalent bonds because carbon has an atomic number 6 and have 4 electrons in its octet so it can neither lose nor gain 4 electrons to complete it's octet so it forms covalent bonds by sharing it's 4 electrons and covalent bonds are more stronger than the ionic bonds…

25. Draw the diagram of the arrangement of the apparatus showing the reaction of steam on metal. Label the following.

(i) Metal Sample (ii) Delivery tube

Ans:

X. Answer the following question. 1 x 4 = 4

26. a) What are alloys? Name the alloy which has lead and tin as its constituent and write one of its uses.

Ans:

· Alloys are the homogeneous mixture of two or more metals or a non metal.

· Solder is the alloy which has lead and tin as it's constituent .

· One use of solder is used to create electrical joints

b) What is an amphoteric oxide? Write any two chemical properties of metals

ans:

Oxides of metals which have both acidic as well as basic behaviour are known as amphoteric oxides

Many metals produce metal oxide by burning in the oxygen of the air. Highly reactive metals react violently when they’re burnt in oxygen.
Metals produce metal oxide and hydrogen gas while reacting with water.
Soluble metal oxides dissolve in water and create metal hydroxide.

PART C: BIOLOGY

XI. 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 practice of using used materials without changing their shape and form is

A. Reuse B. Recycling C. Repurpose D. Reduce

Ans: A. Reuse

28. The correct statement with respect to biodegradable substances among the following is; these substances

A. remain inert in the environment for a long time

B. harm various organisms in the ecosystem

C. increase the density of harmful chemicals in different tropic levels

D. undergo recycling naturally in the environment

Ans: D. undergo recycling naturally in the environment

XII. Answer the following questions. 3 x 1 = 3

29. How is ozone layer formed in the atmosphere?

Ans:

"It is created when ultraviolet radiation (sunlight) strikes the stratosphere, dissociating or splitting oxygen molecules (0₂) to atomic oxygen (0). The atomic oxygen quickly combines with further oxygen molecules to form ozone."

30. Forests are called ‘biodiversity hotspots’. Why?

Ans:

Forests are considered 'biodiversity hot spots' because large number of life forms (such as bacteria, fungi, fern, nematodes, insects, birds, reptiles, mammals, gymnosperms and angiosperms) are found there.

31. Mention any two problems caused by the construction of huge dams.

Ans:

Environmental problem - deforestation leading to loss of biodiversity.
Social problem - nearby towns and villages becomes homeless.

XIII. Answer the following questions. 2 x 2 = 4

32. The tendrils of pea plants appear to move in a particular direction as they grow. How is this response caused?

Ans:

The growth in a plant part in response to touch is called thigmotropism movement. Such movements are seen in tendrils of climbers. The differential rate of cell division in different parts of the tendril happens due to action of auxin. Auxin move to non-touching cells. The non-touching cells elongate faster to curl around the support stick. A thigmonastic response is a touch response independent of the direction of stimulus.

How does adrenal gland bring the chemical coordination in our body? Explain briefly

Ans:

In case of flight or fight reaction to an emergency situation, Adrenal glands release adrenaline into blood which acts on heart and other tissues causes faster heart beat. more oxygen to muscles reduced blood supply to digestive system and skin diversion of blood to skeletal muscles increase in breathing rate.

33. Draw the diagram showing the longitudinal section of a typical flower and label ‘anther’.

Ans:

XIV. Answer the following questions. 3 x 3 = 9

34. ‘Having two sets of genes in the germ cells is not possible’. Clarify this statement with reasons.

Ans:

In humans, germ cells are haploid in nature or has a single set of genes or chromosomes, 23 in number.

Germ cells are cells of the body, that generates gametes or reproductive units. Germ cells, are generated by the process of meiosis. As a result the set of genes or chromosomes in germ cell are always half to that in the somatic cells.

‘Genetic drift’ and ‘natural selection’ together result in the formation of new species of organisms. How? Explain.

Ans:

Natural selection and genetic drift both result in a change in the frequency of alleles in a population, so both are mechanisms of evolution. Genetic drift causes evolution by random chance due to sampling error, whereas natural selection causes evolution on the basis of fitness.

Natural selection is the process through which populations of living organisms adapt and change. Through this process of natural selection, favorable traits are transmitted through generations. Natural selection can lead to speciation.

35. What is the function of ‘Prostate gland’ and ‘testicles’, in human male reproductive system? What measures can be followed by man to avoid the transfer of sperms into the uterus of a woman?

Ans:

The prostate's most important function is the production of a fluid that, together with sperm cells from the testicles and fluids from other glands, makes up semen.

· Testicles produce male gametes i.e. the sperms and also responsible producing a hormone called testosterone.

· The measures can be followed by man to avoid the transfer of sperms into the uterus of a woman is that using condom.

What is sexual maturation? How does menstruation occur? What is the function of placenta during pregnancy?

Ans:

Sexual maturity is the capability of an organism to reproduce.

Menstruation occurs in cycles. The ovaries prepare an egg for release and the womb prepares a lining to nourish the egg if it is fertilized. When the egg is not fertilised, the lining of the womb is shed and a woman gets her menstrual bleeding.

The placenta is an organ that develops in your uterus during pregnancy. This structure provides oxygen and nutrients to your growing baby and removes waste products from your baby's blood. The placenta attaches to the wall of your uterus, and your baby's umbilical cord arises from it.

36. a) How are the studies of anatomical structures helpful for tracing evolutionary relationships?

Ans:

The anatomical structures and physiological functions of different species provide evidence of evolution. Scientists compare and contrast types of anatomical features, known as homologous structures, vestigial structures, and analogous structures, to figure out how closely related different organisms. Similarities in anatomical structures of different species signify that the two species have a relatively recent common ancestor.

b) How could we determine that ‘the birds are very closely related to reptiles’?

Ans:

Feather provided insulation to dinosaurs in cold weather. Later in the evolutionary process, feathers were used for flight in birds. Because dinosaurs were reptiles, it means that birds are closely related to reptiles.
They reproduce by depositing eggs. The laid eggs are coated with calcium.
Both birds and reptiles breathing process is same that is they breathe via lungs.
Reptiles have Circulatory system as same like birds. i.e. they have four chambered heart.

XV . Answer the following question. 1 x 4 = 4

37. Draw the diagram showing the longitudinal section of the human brain. Label the following parts. i) Hypothalamus ii) Medulla

Ans:

XVI. Answer the following questions. 1 x 5 = 5

38. a) What are the functions of the fluids `blood’ and `lymph’ in humans? What are the different waste materials added to the urine from the blood?

Ans:

blood

Regulates the pH by interacting with acids and bases.

Involved in the transportation of hormones, nutrition, enzymes, respiratory gases and other molecules to the respective parts of the body.

lymph

Removes metabolic wastes from the tissue cells.
It helps in invading the entry of pathogenic infections caused by microbes.

Urine is an aqueous solution of greater than 95% water. Other constituents include urea, chloride, sodium, potassium, creatinine and other dissolved ions, and inorganic and organic compounds.

b) How are waste materials excreted in plants?

Ans:

· Excess of water is also excreted from the plant body through the stomatal pores and from the surfaces of fruits and stems. The process of elimination of water is called transpiration.

· The gums, oils, latex, resins, etc. are some waste products stored in plant parts like barks, stems, leaves, etc. Eventually, plants shed off these parts.

· Aquatic plants excrete metabolic wastes through diffusion. Terrestrial plants excrete into the soil.

· Excess carbon dioxide and oxygen are excreted from the plant through the stomata in the leaves.