KSEEB - 10 SCIENCE - MODEL QUESTION PAPER - 2 - KEY ANSWER

 

    KSEEB - 10 SCIENCE     

      MODEL QUESTION PAPER - 2  (25-26)     

         KEY ANSWER       

        PART - A PHYSICS      

I. Multiple choice questions: 2 × 1 = 2

1. The S I unit of electric current is 

(A) ampere (A) 

(B) ohm (Ω)

(C) volt (V)

(D)  watt (W)

Ans:  (A) ampere (A)

2. Observe the figure given below. The magnetic field at the centre ‘C’ of circular coil is  

(A) zero    (B) I     (C) I1    (D) I2 

Ans: (A) zero

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

3. Which mirror is used as rear view mirror? 

Ans:   Convex mirror.

4. List any two suggestions to avoid the overload in domestic electric circuit. 

Ans:

★ Live and neutral wires should not come into direct contact.

★ Too many appliances should not be connected to a single socket.

★ Should always use quality wires and good quality electrical appliances.   (Any two) 

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

5. Draw a simple electric circuit. Label ammeter and voltmeter. 

Ans:

6. An electric motor receives 10A electric current from 220V electric source. Find the power of motor.

Ans:

Given:

I = 10A

V = 220V

P = ?

P = V × I

P = 220 × 10 = 2200W

7. Draw a diagram of experiment conducted by Newton to show the recombination of white light. 

Ans:

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

8. a) State two laws of reflection of light. 

b) What is magnification of mirror? What does the negative sign indicate in the magnification value? 

OR 

Explain the activity which shows the refraction of light through a glass slab.    

Ans:

a) 

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 

b)

★ The relative extent to which the image of an object is magnified with respect to the size of the object. / It is the ratio of height (size) of the image to the height (size) of the object. / Ratio of object distance and image distance

★ indicates that the image is real and inverted.

OR

★ Fix a sheet of white paper on a drawing board using drawing pins.

★ Place a rectangular glass slab over the sheet in the middle. Draw the outline of the slab with a pencil. Let us name the outline as ABCD.

★ Take four identical pins and fix two pins, say E and F, vertically such that the line joining the pins is inclined to the edge AB.

★Look for the images of the pins E and F through the opposite edge. Fix two other pins, say G and H, such that these pins and the images of E and F lie on a straight line.

★Remove the pins and the slab. Join the positions of tip of the pins E and F and produce the line up to AB. Let EF meet AB at O. Similarly, join the positions of tip of the pins G and H and produce it up to the edge CD. Let HG meet CD at O′.

★ Join O and O′. Also produce EF up to P, as shown by a dotted line.

9. a) What is near-sightedness? 

b) What is power of accommodation of eye?  How does the eye accommodate to see distant objects? 

OR 

Stars appear to twinkle but the planets do not twinkle. Why? 

Ans:

a) The eye defect in which a person is able to see nearby objects clearly but not the distant objects.

b) 

★ The ability of the eye lens to adjust its focal length. 

While seeing the distant objects:

★ Ciliary muscles relax.

★ The focal length of the eye lens increases 

★ The eye lens becomes thin. 

OR

★Stars appear as point sources of light because they are very distant. 

★The light from a point source travels through the Earth's atmosphere, which has continuously changing refractive indices (atmospheric refraction). 

★This bending of light is inconsistent and leads to the apparent variation in the star's brightness, causing the twinkling effect.

 

★ Planets are much closer and appear as extended source. 

★ Due to their proximity, the average change in the amount of light reaching the eye from the different point sources of the planet nullifies the twinkling effect, so they do not twinkle.

10. a) What is solenoid? 

b) State Fleming’s left hand rule. 

c) What is the potential difference between live wire and neutral wire in domestic electric circuit in our country? 

Ans:

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

b) Fleming's Left-Hand Rule states that if we stretch the thumb, forefinger, and middle finger of the left hand such that they are mutually perpendicular, the forefinger points in the direction of the magnetic field, the middle finger points in the direction of the current, and the thumb will point in the direction of the force.

c) 220V

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

11. a) State Joule’s law of heating and name four appliances which work on the heating effect of electricity. 

b) Give reason. 

(i)  The tungsten is used almost exclusively for filament of electric lamps. 

(ii) Copper and aluminium wires are usually employed for electricity transmission. 

OR

a) State ohm’s law. List the factors on which the resistance of conductor depends. 

b) “The potential difference between two points is 1V.” Mention the meaning of this statement. 

Ans:

a)

★ The heat produced in a resistor is 

i) directly proportional to the square of the current for a given resistance. 

ii) directly proportional to the resistance for a given circuit. 

iii) directly proportional to the time for which the current flows through the resistor. 

( H = I^2RT formula is written then 1/2 mark )

The devices that work on this law are

★ Electric Toaster

★ Electric Oven

★ Electric Kettle

★ Electric Bulb

★ Electric Fuse ( Any four)  

b)

i)

★ Melting point is more 

★ Resistivity is more. 

ii)

★ ​Copper and Aluminium have very low resistivity.

a) 

★ The potential difference ( V ) across the ends of a given metallic wire in an electric circuit is directly proportional to the current ( I ) flowing through it, provided its temperature remains the same.

V = IR  [ 1 mark can be allotted for formula ]

Factors on which resistance of a conductor depends :

★ Length of a conductor

★ Area of cross-section of a conductor

★ Nature of the material 

★ Temperature.  

b)

★ It means that 1Joule of work is done to move a 1Coulomb of charge from one point to the other. 

12. a) An object is placed perpendicular to principal axis of a convex lens of focal length 20cm. If the distance of image is to be 60cm, then at what distance the object is to be placed from the lens? 

b) The object distance and image distance of a lens are -30cm and -10 cm respectively. Decide the type of lens and nature of image.

Ans:

Given:

Focal length (f) = +20cm

Image distance (v) = +60cm

Object distance (u) =?

The object is to be placed at a distance of 30cm from the lens.  

b)

Given

Object distance (u): -30cm

Image distance (v): -10cm

  

Since the focal length (f) is negative (f = -15cm), the lens is a Concave Lens.

​The magnification for a lens is given by:

A positive magnification indicates that the image is Erect and virtual image

magnification  is less than 1 . This means the image is Diminished.

        PART - B   CHEMISTRY      

VI. Multiple choice questions: 3 × 1 = 3 

13. The functional group present in pentanal is 

(A) - OH     (B)  - CHO     (C)  - COOH    (D)  - CO -

Ans: (B) - CHO 

14. Silver chloride turns grey when exposed to sunlight. This is because silver chloride 

(A) decomposes to form silver.

(B) decomposes to form chlorine

(C) combines with oxygen.

(D) reacts with atmospheric moisture. 

Ans: (A) decomposes to form silver.

15. To make iron to be hard and strong 

(A) carbon is added to pure iron

(B) zinc is added to pure iron

(C) fused with some other metals

(D) anodization will be done 

Ans: (A) carbon is added to pure iron

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

16. Hydrochloric acid is considered as a strong acid. Why? 

Ans:

because it completely dissociates into hydrogen (H+) and chloride (Cl-) ions when dissolved in water.

17. What is roasting in metallurgy? 

Ans:

Roasting is the process of heating a sulphide ore strongly in the presence of excess air to convert it into its oxide.

18. The first member of a group of carbon compounds is CH3Cl. Write the molecular formula and the name of the third member of this group. 

Ans:

★ Molecular formula: C3H7CI

★ Name: 1- Chloropropane

VIII. Answer the following questions:  3x2=6

19. When concentrated sulphuric acid is added to a test tube containing solid sodium chloride the gas ‘X’ will be released. What are the ions formed when this gas is passed into water? What are the products formed when the gas ‘X’ is passed into an aqueous basic solution obtained in the chlor-alkali process?

Ans: 

★ lons formed when passed into water: H+ (or H3O+) and CI ions. 

★ Products: Sodium chloride (NaCI) and Water (H2O)

20. Write the properties of ionic compounds with respect to solubility, melting point, physical state and electrical conductivity. 

OR 

Give reasons. 

(i)  Magnesium metal displaces copper in copper sulphate solution. 

(ii) Sodium metal is stored in kerosene. 

Ans:

★Solubility: Generally soluble in water and insoluble in solvents like kerosene, petrol, etc.

★ Melting Point: Have high melting and boiling points.

★Physical State: Exist as solids and are usually brittle.

★ Electrical Conductivity: Conduct electricity in the molten state and in aqueous solution, but not in the solid state

OR

(i) Magnesium is more reactive than copper. Therefore, Mg can displace Cu from its salt solution

(ii) Sodium metal is highly reactive and reacts vigorously with oxygen and moisture (water) present in the air.

21. Explain the cleansing action of soap on dirt. 

OR

Carbon atoms do not form C 4 + cation ions or C 4 - anions. Why? 

Ans:

★ The molecules of soap are sodium or potassium salts of long chain carboxylic acids.

★ The ionic end of soap interacts with water while the carbon chain interacts with oil.

★ The soap molecules thus form structure called micelles. This forms an emulsion in water.

★ The soap micelles thus helps in pulling out the dirt in water and we can wash our clothes clean.

OR

★ Carbon cannot form C4+ cation because of removal of 4 elections from a carbon atom would require a large amount of energy.

★  Carbon cannot form C4- anion because it would be difficult for the nucleus with 6 protons to hold on to 10 electrons.

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

22. Balance the following equations 

OR

Convert the following chemical reactions into chemical equations. 

(i) Copper reacts with concentrated nitric acid.

(i) Silver nitrate solution is added to potassium bromide solution.  

(ii) Zinc oxide is reduced by coke. 

Ans:

(i) 3Mg + N2→ Mg3N2 

(ii) 2NaOH + H2SO4 → Na2SO4 + 2H2O 

(iii) 2AI(OH)3 → Al2O3 + 3H2O

OR

(i) Cu + 4HNO3 → Cu(NO3)2 + 2NO2 + 2H2O

(ii) AgNO3(aq) + KBr (aq) → AgBr (s) + KNO3(aq)

(iii) ZnO(s) + C(s)  → Zn(s) + CO(g)

23. a) What is acid rain? 

b) Which gas is liberated when an acid reacts with a metal carbonate? 

c) Write the chemical name and molecular formula of baking soda. 

Ans:

a) pH of rain water is less than 5.6, it is called acid rain.

b) Carbon dioxide

c)

★ Sodium Bicarbonate

★ NaHCO3

24. Draw the diagram of the arrangement of apparatus used to show the action of steam on a metal. Label the following parts. (i)  Glass-wool soaked in water  (ii) Delivery tube

Ans:

X. Answer the following questions :  1x 4 = 4 

a) How many single bonds and double bonds are there in the molecule of C3H7COOH? 

b) Write the structural formulae of cyclopentane and propanol. 

c) Name the substance that do not undergo a chemical change that is used in the reaction of converting a compound containing a carbon-carbon double bond into a compound containing only single bonds. Write an example for this reaction in the form of an equation. 

Ans:

a)

★ Single bonds: 12

★ Double bonds: 1

b) Cyclopentane:

propanol:

c)

★  The substance is a catalyst, Palladium (Pd) or Nickel (Ni).

      PART - C  BIOLOGY     

XI. Multiple choice questions: 2 × 1 = 2

26. Observe the figure below. The characteristic and function of the structure ‘X’ are respectively

(A) wall is absent and pollinates.    

(B) it has a thick wall and grows into a new rhizopus. 

(C) it has a thin wall and grows into a new rhizopus. 

(D) it has a thick wall and pollinates. 

Ans: (B) it has a thick wall and grows into a new rhizopus. 

27. The correct statement regarding bile juice among the following is, this juice is secreted by the 

   

(A) stomach and acidifies food. 

(B) stomach and alkalises food. 

(C) liver and alkalises food. 

(D) pancreas and alkalises food. 

Ans: (C) liver and alkalises food. 

28. The correct statement/s about gene among the following is/are     

(i) It is an unit of DNA. 

(ii) It is the source of information for protein. 

(iii) A single gene synthesizes several proteins. 

(iv) It functions as an enzyme. 

(A) (i) only    

(B) (i) and (ii) only 

(C) (ii), (iii) and (iv) only 

(D) (i), (ii) and (iii) only 

Ans: (B) (i) and (ii) only

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

29. What is DNA replication? 

Ans:

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

30. What is the relationship between the amount of haemoglobin in the blood and the amount of ATP released in the human body?

Ans:

★Haemoglobin carries oxygen to the cells. Oxygen is essential for the complete breakdown of glucose

★more haemoglobin means more oxygen delivery, which increases the amount of ATP produced during cellular respiration.

31. What is the function of abscisic acid in plants? 

Ans: Abscisic acid inhibits growth in plants. 

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

32. Draw a diagram showing the structure of a nephron. Label glomerulus.

Ans: 

33. a) Name the prominent parts of reflex arc.

b) Which hormones are responsible for sexual maturation in humans?

Ans:

a) Receptor, Sensory neuron, Spinal cord, Relay neuron, Motor neuron and Effector

b) Testosterone (in males), Estrogen and Progesterone (in females)  

XIV. Answer the following questions : 3x3=9

34. Draw the diagram showing the structure of human brain. Label the following parts. (i) Cerebrum  (ii) Pons 

Ans:

35. Red flowering tall pea plant (TTRR) is hybridised with white flowering dwarf pea plant (ttrr). Show the result of F2 generation with the help of a checker board and write the ratio of verities of plants. 

OR 

Yellow seeds producing pea plant (YY) is hybridised with green seeds producing pea plant (yy). Show the result of F2 generation with the help of a checker board. Write the phenotypic and genotypic ratios of F2 generation. 

Ans:

The ratio of varieties of plants is = 9 : 3 : 3 : 1

OR

​Phenotypic Ratio: 3 : 1

Genotypic Ratio: 1 : 2 : 1 

36. a) What are biodegradable substances? 

b) Which synthetic chemical is responsible for the depletion of the ozone layer? 

c) Write two examples of decomposers.

Ans:

a) Substances that are broken down by biological processes are said to be biodegradable.

b) Chlorofluorocarbons (CFCs)

c) Bacteria, Fungi

XV. Answer the following questions : 1 x 4 = 4 

37. a) What are the functions of the aorta and pulmonary veins? 

b) State the events that occur during the photosynthesis in plants. 

OR

a) In the first stage of cellular respiration, the glucose molecule is broken down into which molecule in the cytoplasm?  How is this broken molecule breaks down in muscle cells? 

b) Write any two differences between xylem and phloem. 

Ans:

a)

★carry oxygenated blood from the left ventricle of the heart to all parts of the body.

★ carry oxygenated blood from the lungs  to the left atrium of the heart.

b) 

★ Absorption of light energy by chlorophyll.

​

★ Conversion of light energy to chemical energy and the splitting of water molecules into hydrogen and oxygen.

​

★Reduction of carbon dioxide to carbohydrates

OR

a)

★ Pyruvate

b)

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

38.  a) What is the role of the placenta at the development stage of the embryo in the female uterus? 

b) Testes are located outside the abdominal cavity in males. Why? 

c) How is the number of chromosomes reestablished in sexual reproduction? Explain. 

OR

a) How are the reproductive processes in hydra and planaria differ? 

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

c) How does a seed grows into future plant? 

Ans:

a)

★ Provide glucose and oxygen to pass from mother to embryo.

★ Removes the wastes generated from the embryo.

b) to maintain the temperature required for sperm production. 

c)

★ The chromosome number is reestablished in sexual reproduction through meiosis and fertilization. 

★ Meiosis reduces the chromosome number to half in gametes. 

★ During fertilization, the sperm and egg fuse to form a diploid zygote, restoring the original chromosome number.

OR

a)

Hydra: 

★ Reproduces asexually primarily by Budding. 

★ A small outgrowth (bud) develops from the parent body, which detaches upon maturation to form a new individual.

Planaria: 

★Reproduces asexually primarily by Regeneration. 

★ If the body is cut into several pieces, each piece can grow into a complete new organism. 

b)

★ Zygote develops into the embryo. 

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

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

c)

★ A seed grows into a future plant through the process of Germination.

★ Radicle grows downwards to form the root system.

★ Plumule grows upwards to form the shoot system