MG SCHOOL SCIENCE : KSEEB - 10 SCIENCE - MODEL QUESTION PAPER - 3

KSEEB - 10 SCIENCE

MODEL QUESTION PAPER - 3 (25-26)

KEY ANSWER

PART - A PHYSICS

I. Multiple choice questions: 2 × 1 = 2

1. A mirror produces erect and enlarged image of an object. Then the type of mirror and the nature of that image is respectively

(A) Convex mirror and virtual image

(B) Concave mirror and real image

(D) Concave mirror and virtual image

Ans: (D) Concave mirror and virtual image

2. The rate of energy consumed in an electrical circuit is, electric.

(A) current (B) potential difference

Ans: (D) power

II. Answer the following questions: 2×1=2

3. Draw the symbols of the following components used in an electrical circuit.

i) Rheostat ii) Wires crossing without joining

Ans:

4. What happens if the fuse is connected to the neutral wire instead of connecting to the live wire in the meter board of the house?

Ans: The appliance remains live and dangerous even when the fuse blows.

III. Answer the following questions: 3×2=6

5. a) Define the phenomenon expressed in below given figure. Which colour does H and M represent here?

Ans:

★ Phenomenon: Dispersion of light

★ H represents Red

★ M represents Blue

6. How does the resistance of a conductor related to the length of the conductor and the area of cross-section of that conductor?

The resistivity of some materials found at 20^o C is given in the table below. Look at it and answer the questions given below.

a) Which is the better conductor among silver and copper? Why?

b) Alloys are used in electric heating devices. Why?

Ans:

The resistance (R) of a conductor is:

★ Directly proportional to the length (L) of the conductor.

★ Inversely proportional to the area of cross-section (A) of the conductor.

★ Silver is the better conductor.

★ It has lower resistivity.

★ They have high resistivity and high melting point.

★ They do not oxidize (do not burn easily) at high temperatures.

7. One end of the bar magnet is brought near the south pole of a magnetic needle. Then this end of the magnetic needle deflects away from the end of the bar magnet. Name the pole of the bar magnet that has been directed towards the south pole of this magnetic needle. Give reason for your answer.

Ans:

★ South pole

★ like poles repel each other.

IV. Answer the following questions: 3×3=9

8. Draw the diagram to show the image formation when an object is placed between 2F1 and F1 of a convex lens. Mention the position and size of the image formed. (F1 -principal focus of lens)

Ans:

Position of the image: Beyond 2F2

Size of the image: Enlarged

9. What is presbyopia? Mention the reasons and suggest a remedy for this defect?

What is short-sightedness? What are the reasons for this defect? How can it be corrected?

Ans:

It is the defect of vision where an eye loses its power of accommodation and the person cannot see near objects comfortably and distinctly.

Reasons:

★ Gradual weakening of the ciliary muscles.

★ Decreasing flexibility of the eye lens.

Remedy:

★ This defect is corrected by using a bifocal lens.

It is the defect of vision in which a person can see near objects clearly but cannot see distant objects distinctly.

Reasons:

★ Excessive curvature of the eye lens

★ Elongation of the eyeball.

★ Correction: It can be corrected by using a concave lens

10. a) What are the reasons for overloading in an electric circuit?

b) What is solenoid? How can electromagnet be prepared from a solenoid?

a) Mention the properties of magnetic field lines.

b) When the number of turns of a current carrying circular loop is increased by ten times what change occurs in the magnetic field produced in it?

Ans:

★ Accidental hike in the supply voltage.

★ Connecting too many appliances to a single socket.

★ When live wire and neutral wire come into direct contact. (Any two)

★ A coil of many circular turns of insulated copper wire wrapped closely in the shape of a cylinder is called a solenoid.

★ By replacing permanent magnet with an electromagnet.

Properties of the magnetic field lines :

★ emerge from north pole and merge at the south pole.

★ closed curves

★ never intersect each other

★ have magnitude and direction.

★ producing magnetic field increases by 10 times.

V. Answer the following questions: 2×4=8

11. a) What is reflection of light?

b) State the laws of reflection of light.

c) What is the focal length of a mirror

a) What is refraction of light?

b) State Snell’s law of refraction.

c) Define the following with respect to a lens. i) Focal point ii) Aperture

Ans:

a) Reflection of light is the phenomenon where light rays bounce back into the same medium after hitting a surface. / Bounce back of light when light fall on reflecting surface.

i) The angle of incidence is equal to the angle of reflection.

ii) The incident ray, the normal to the mirror at the point of incidence and the reflected ray, all lie in the same plane

c) It is the distance between the pole (P) of the mirror and the principal focus (F) of the mirror.

a) It is the phenomenon of the change in the direction (bending) of light when it travels obliquely from one transparent medium to another.

Snell's law states that the ratio of the sine of the angle of incidence (\sin i) to the sine of the angle of refraction (\sin r) is a constant for the light of a given colour and for a given pair of media. /

Sin i / Sin r = Constant

Focal point : It is the point on the principal axis of the lens where light rays parallel to the principal axis converge or appear to diverge from after passing through the lens.

Aperture: The effective diameter of the circular outline of a spherical lens is called its aperture.

12. a) Observe the diagram of below given electric circuit. Find the total resistance and the total current of the circuit.

b) An electric fan rated 50 W is used for 6 hours in a day. What is the cost of the energy it consumes for 30 days at Rs.4 per 1kWh?

Ans:

Power of fan, P = 50 W = 0.05 kW

Time, t = 6 hours

Energy = Power × Time

= 0.05 kW × 6 hours

= 0.3 kWh per day

Energy used in 30 days

= 0.3 kWh × 30

= 9 kWh

Cost of energy

Rate = Rs. 4 per kWh

Cost = 9 × 4 = Rs. 36

PART - B CHEMISTRY

VI. Multiple choice questions 3×1=3

13. The chemical formula of bleaching powder is

(A) NaCl (B) Na2CO3

Ans: (D) CaOCl2

14. CuSO4 + Fe → FeSO4 + Cu

2AgNO3 + Cu → Cu(NO3)2 +2Ag

(A) Copper is more reactive than iron and silver

(B) Iron is less reactive than copper and silver

(D) Silver is more reactive than copper and iron.

Ans: (C) Copper is more reactive than silver but less reactive than iron

15. Another structure with the same molecular formula of the compound in the following structural formulas

Ans: (D)

VII. Answer the following questions: 3×1=3

16. What is the reason for the formation of brown coloured fume in the experiment shown through the below given figure?

Ans:

The brown coloured fumes are due to the formation of Nitrogen dioxide (NO2) gas.

17. Name any two metals that are available in the pure form in the nature.

Ans: Gold (Au) and Platinum (Pt)

18. What is the significance of hydrogenation?

Ans:

It is used in the industrial production of vegetable ghee from liquid vegetable oils.

VIII. Answer the following questions: 3×2=6

19. A solution of baking soda is commonly applied to the area of a honeybee stung area. Justify this action.

Ans: Baking soda is a mild base, neutralize the acidic liquid from the sting,

20. How is pure mercury obtained from cinnabar?

(OR)

Why the calcium does not catches fire when it reacts with water?

Ans:

Roasting: Cinnabar is heated in air, converting it to mercuric oxide.

Reduction: Mercuric oxide is further heated, which reduces it to pure mercury metal. /

★ Calcium (Ca) reacts with water less violently.

★ When calcium reacts with water, the heat produced is not sufficient to ignite the hydrogen gas that is formed.

21. Carbon compounds are found in the larger number in the nature. Why? Clarify the reasons.

Ans:

Due to two unique properties of the carbon atom:

★ Catenation: Carbon has the ability to bond with other carbon atoms to form long chains, branched chains, and closed rings.

★ Tetravalency: Carbon has a valency of four, it can bond with four other atoms including carbon, hydrogen, oxygen, nitrogen, etc.

This allows for the formation of an almost infinite number of different carbon compounds.

IX. Answer the following questions: 3×3=9

22. a) Magnesium ribbon burns with a dazzling white flame in the air and changes into magnesium oxide. Mention the type of this reactions.

b) List out the observations that help us to determine that a chemical reaction has been taken place.

a) Chemical equations have to be balanced. Why?

b) Mention the measures that are followed to prevent rusting of iron.

Ans:

a) Combination reaction / Oxidation reaction

★ Change in state

★ Change in colour

★ Evolution of a gas

★ Change in temperature

a) to satisfy the Law of Conservation of Mass.

★ Painting

★ Greasing

★ Oiling

★ Galvanisation

★ Electroplating

★ Alloying (Any four)

23. Draw the diagram to show the reaction of the zinc granules with dilute sulphuric acid and testing hydrogen gas by burning. Label the following parts. i) Zinc granules ii) Delivery tube

Ans:

24. a) Show the formation of magnesium chloride molecule by transfer of electrons.

b) Aluminium oxide is called an amphoteric oxide. Why?

Ans:

b) Because Aluminium oxides react with both acids and as well as bases to produce salt and water.

X. Answer the following question: 1×4=4

25. a) Write any two differences between saturated and unsaturated carbon compounds.

b) Write the molecular formula and structural formula of the following carbon compounds. i) Propanoic acid ii) Cyclohexane

Ans:

i) Molecular formula: C3H6O2

Structural formula:

ii) Molecular formula: C6H12

Structural formula:

PART - C BIOLOGY

XI. Multiple choice questions 3×1=3

26. The function of stomata among the following is

(A) Exchange of gases

(B) Transportation of water and food

(D) Establishing osmotic pressure

Ans: (A) Exchange of gases

27. The plant hormone responsible for phototropism in plants is

(A) Auxin

(B) Cytokinin

(D) Gibberellin

Ans: (A) Auxin

29. A common bacterial infection that spreads through sexual contact in human beings is

(A) Gonorrhoea (B) AIDS

Ans: (A) Gonorrhoea

XII. Answer the following questions: 3×1=3

29. Double circulation of the blood is essential to maintain constant temperature in mammals. How?

Ans:

Oxygenated and deoxygenated blood will not mix together. Efficient supply of oxygen to the body. Helpful to maintain body temperature.

30. “Is Self-pollination possible in flowers that have only stamens?” Justify your answer.

Ans:

No, Self-pollination requires both the male (stamen), and the female reproductive part (pistil).

31. What is DNA replication?

Ans:

The process of giving rise to new DNA from the DNA of mother cell during interphase of cell division.

XIII. Answer the following questions: 2×2=4

32. Draw the diagram to show the structure the structure of the nephron and label the part Bowman’s capsule.

Ans:

33. What is reflex arc? In many animals reflex arcs have been found an effective way of functioning. Why?

Ans:

★ The pathway taken by the nerve impulse during a reflex action is called reflex arc.

★ The impulse travels through the spinal cord instead of the brain, saving time. This allows animals to react immediately to danger

XIV. Answer the following questions: 3×3=9

34. Draw the diagrams to show the structure of human brain. Label the following parts

i) Hypothalamus ii) Pons

Ans:

35. a) Father only determines the sex of a child. Why?

b) Yellow seed producing pea plant (YY) is crossed with green seed producing plant (yy). Then draw a checker board showing the results obtained in F2 generation.

(OR)

Red flowering tall pea plant (TTRR) is hybridised with white flowering short pea plant (ttrr). Then draw a checker board showing the results obtained in F2 generation.

Ans:

a) Because only the father produces both X and Y sperm, he alone determines whether the child will be a boy or a girl.

(OR)

36. a) Grass → Frog → Snake; If the amount of energy in the first trophic level of this food chain is about 100 J, What is the amount of the energy available for the organism at the third trophic level?

b) If all the wastes we generate are biodegradable, what kind of the effects this would impact on our environment? Discuss.

Ans:

a) 1 J.

Positive effects:

★ Cleaner soil and surroundings

★ No need for burning

★ Adds nutrients back to the soil

Negative effects:

★ Greenhouse gas emissions

★ Foul smell

★ Breeding of flies and spread of diseases

XV. Answer the following question : 1×4=4

a) How are inorganic substances transported from the xylem tissue in plants? Explain.

b) Write any four methods used by plants to eliminate waste materials.

a) Explain the digestion process in the small intestine of humans.

b) What is the main function of alveoli in the human lungs?

Ans:

★ In xylem tissue, vessels and tracheids of the roots, stem and leaves are interconnected to form a continuous system of water-conducting channel reaching all parts of the plant.

★ Transpiration creates suction pressure and creates a column of water. This steadily pushes the water upward with dissolved minerals in it.

★ Excess of water removed by transpiration

★ Remove oxygen and carbon dioxide gases through stomata

★ Waste products and dead cells in vacuoles by shedding leaves / barks

★ Resins and gums get store in old xylem

★ Diffusing certain wastes into surrounding soil (Any four)

★ Small intestine is the site of complete digestion of proteins, carbohydrates and fats.

★ Enzymes in the intestinal juice convert proteins into amino acids, complex carbohydrates into glucose and fats into fatty acids and glycerol.

★ Digested food is absorbed by the villi present in the walls of intestine.

b) The alveoli contain network of blood capillaries that increase the surface area for exchange of gases.

XVI. Answer the following questions: 1×5=5

38. a) How do daughter organisms produced in hydra, spirogyra and amoeba? Explain briefly.

b) What are the changes that occur in a flower after fertilization?

a) How does a fertilized egg in a female develop into an embryo in the uterus? How does this embryo get nourishment in the mother’s womb? Explain

b) Explain the important functions of

i) Testis and

ii) Seminal vesicle in male reproductive system in humans.

Ans:

Hydra: A small outgrowth called a bud develops on the parent body. This bud gradually develop and detaches from the parent.

spirogyra: The body of the Spirogyra simply breaks up into two or more smaller pieces upon maturation. Each fragment grows into a new individual.

Amoeba: The cell divides into two equal halves. First, the nucleus divides into two, followed by the division of the cytoplasm, resulting in two daughter Amoeba.

★ Ovum develops into seed. Ovary grows rapidly and ripens into fruit.

★ Petals, sepals, stamen, style and stigma may shrivel and fall off.

★ The fertilised egg (Zygote) starts dividing and forms an embryo.

★ The embryo is implanted in the lining of the uterus.

★ It continues to grow and develop organs to become foetus.

Nourishment :

★With the help of a special disc shaped tissue called placenta.

★ It contains villi on the embryo’s side and blood spaces on the mother’s side.

★This provides glucose and oxygen to the developing embryo.

Testis:

★ Production of sperms / male gametes.

★ Controls the production of testosterone.