SCIENCE MQP CHAPTERWISE 2024 - 25 and 2025 - 26

    KSEEB     

    SCIENCE MODEL QUESTION PAPERS 1 -2-3-4    

       CHAPTER WISE     

Click Below To Download 👇

👉 YEAR - 2024 - 25

👉 YEAR - 2025 - 26

Click Here to KEY ANSWER

KSEEB - 10 SCIENCE - MODEL QUESTION PAPER - 4 - KEY ANSWER

           KSEEB - 10 SCIENCE             

           MODEL QUESTION PAPER - 4 (25-26)    

                     KEY ANSWER                 

                 PART - A PHYSICS        

I. Multiple choice questions: 2 × 1 = 2

1. The diameter of the reflecting surface of a spherical mirror is    

 (A) pole of the mirror 

 (B) centre of curvature 

 (C) principal axis 

 (D) aperture

Ans: (D) aperture

2. When three resistors of different resistance are connected in parallel in an electric circuit and switched on, then the quantity that remains the same in all the resistors is 

(A)  current 

(B) potential difference 

(C) resistance 

(D) resistivity   

Ans: (B) potential difference

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

3. What are the reasons for overload in an electric circuit?

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 )

4. Two situations of freely suspended parallel copper wires carrying current are shown in the figure given below.

In which of these situations, the wires attract each other? Justify your answer. 

Ans:

★ Situation – 1

★Parallel wires carrying currents in the same direction attract each other. Therefore, in this situation, the two wires attract each other.

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

5. What is the colour of danger signal lights? Why is that colour preferred?

Ans:

★ The colour of danger signal lights is red.

★ Because it has the longest wavelength among visible colours so, it gets scattered the least by dust, fog, or air molecules.

6. Among nichrome and copper wires, which of the wires is used in electric fan and in the coils of electric heater? Why?

Ans:

★ Copper wire is used in the electric fan because It has low resistivity.

★ Nichrome wire is used in the coils of the electric heater because It has high resistivity and high melting point.

7. Draw the diagram indicating the field lines of the magnetic field around a current carrying straight conductor.

Ans:

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

8. Draw the ray diagram to show the image formation when an object is kept between ‘C’ and ‘F’ of a concave mirror. Write the nature and size of the image formed. [C = Centre of curvature, F = Principal Focus]

Ans:

Size of the image: Larger

Nature of the image : read and inverted.

9. Explain an experiment to demonstrate that a current carrying conductor placed in a magnetic field experiences a force. 

OR 

Explain an activity to draw the magnetic field lines around a bar magnet using a compass needle.

Ans:

★ Take a small aluminium rod and suspend it horizontally using connecting wires.

★ Place a strong horse-shoe magnet in such a way that rod lies between the two poles with the magnetic field directed upwards. 

★ Connect the aluminium rod in series with a battery, a key and a rheostat. 

★ Now pass the current through the aluminium rod in one particular direction. 

★ The rod displaces towards one side. 

★ Reverse the direction of current flowing through the rod. The rod displaces towards the opposite side.  

OR

★ Place a bar magnet on a white paper and mark the boundary of the magnet 

★ Place the compass needle near the north pole of the magnet. The south pole of the compass needle directs towards the north pole of the magnet. Mark it with a point. 

★ Move the needle to a new position such that its south pole occupies the position previously occupied by its north pole. Mark it with a point. 

★ In this way proceed step by step till you reach the south pole of the magnet. 

★ Join the points marked on the paper by a small curve. 

★ This curve represents a field line

10. A student clearly reads letters of a textbook only when the book is kept at a distance more than 50 cm from his eyes without difficulty. Then, 

i) identify this defect of the eye. 

ii) suggest a remedy for this defect.

b) When sunlight passes through the trees of a dense forest on a foggy morning then the path of the beam of light appears between the trees. 

i) What is this phenomenon called? 

ii) The same phenomenon is not normally visible in an open field. Why? Write your analysis.

OR 

a) The position of the stars changes apparently in the clear sky. Why? Explain. 

b) White light is passed through the given arrangement of three glass prisms (X, Y, and Z) as shown in the figure given below.

i) Is spectrum of light seen on the screen? 

ii) What is the role of prism Z?

Ans:

a) 

i) defect is Hypermetropia

ii) This defect is corrected by using a  convex lens

b)

i) This is called the Tyndall effect

ii) In an open field, the air is usually clearer and contains fewer suspended particles. Since scattering is very low, the light does not become visible as a beam.

OR

a)

★ It is due to atmospheric refraction of starlight. 

★ The starlight on entering the earth’s atmosphere, undergoes refraction continuously before it reaches the earth. 

★ The atmospheric refraction occurs in a medium of gradually changing refractive index 

★ As the path of rays of light coming from the star goes on varying slightly, the apparent position of the star fluctuates and the amount of starlight entering the eye flickers. This is the twinkling effect of stars.  

b)

i) Yes / The spectrum of light forms on the screen

ii) Prism Z disperses this white light into 7 colours and hence we see the spectrum of light on the screen.  

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

11. a) What is magnification? Write the formula to calculate magnification of the image produced by a lens.

b) State the laws of reflection of light.

Ans:

a)

★ It is the ratio of the height of the image to the height of the object.

★ M = h'/h = v/u

b)

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 

12. a) Two resistors of resistance 10Ω and 40Ω are connected in series and connected to a 12V battery. Calculate the equivalent resistance in the electric circuit and the total current flowing in the circuit. 

b) A washing machine rated 500W is used for 2 hours a day for 30 days. Calculate the cost of using this appliance at 3 Rs per 1 kWh. 

OR 

a) Resistance of a metal wire of length 2 m is 28 Ω at 20°C. If the diameter of the wire is 0.04 mm then, what will be the resistivity of the metal at that temperature? 

b) 1000 J of heat is produced each 2 seconds in a 5Ω resistor. Find the potential difference across the resistor.

Ans:

a)

Given: 

R1 = 10 Ω

R2 = 40 Ω

V = 12 V

Equivalent Resistance: 

Rs = R1 + R2 = 10 + 40 = 50 Ω

Total Current:

I = V / Rs

I = 12 / 50 

I =  0.24 A

b)

Given:

P = 500W = 0.5 kW

t = 2h × 30 days = 60h

E = P × t 

E = 0.5kW × 60h = 30kWh

Cost = 30kWh × 3Rs = 90Rs

OR

a)

b)

Given:

H = 1000j

R = 5Ω

t = 2s

H = I2 R T

I2 = H/Rt

I = √ 1000/5×2 = 10 A

V = I R = 10A × 5 = 50V

                  PART - B CHEMISTRY        

VI. Multiple choice questions:   3 × 1 = 3 

13. As the pH value of a neutral solution increases, 

(A)    basic property decreases and number of OH− ions increases. 

(B) acidic property increases and number of H+ ions decreases. 

(C)  basic property increases and number of OH− ions increases. 

(D) acidic property decreases and number of H+ions increases. 

Ans: (C) basic property increases and number of OH− ions increases. 

14. The X in the following reaction represents, 

(A)  K2Cr2O7               (B) KMnO4 

(C) NaOH                     (D) KOH 

Ans: (B) KMnO4

15. To make pure iron hard and strong, the substance that is to be added to it is 

(A)  carbon       (B)  zinc     

(C) nickel           (D) tin

Ans: (A) carbon

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

16. What is rancidity?

Ans: Rancidity is the process of oxidation of oils and fats in food materials, which leads to a change in their smell and taste.

17. Write the structural formula of the compound obtained when one atom of hydrogen in ‘ethane’ is replaced by −CHO group. 

Ans:

18. Aluminium articles do not corrode easily like iron articles. Justify.

Ans:

Because aluminium reacts with the oxygen in the air to form a thin, strong, and protective layer of aluminium oxide  on its surface. This oxide layer is highly resistant to further corrosion.

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

19. Analyze the list of experiments in the table given below. In which of the experiments the following salts will be produced? (i)  An acidic salt (ii) A neutral salt 

Ans:

i) Experiment No 1

ii) Experiment No 3

20. Name the catalyst used and the product obtained in the hydrogenation of ethene. 

OR 

The molecular formula of the first member of a homologous series of carbon compounds is CH2O(HCHO). Determine the name and the molecular formula of the third member of this group. Mention the general name of this group.

Ans: 

★ Nickel (Ni) / Palladium (Pd)

★ Ethane 

21. Draw the diagram to show the action of steam on metals.  

Ans:

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

22. Write the balanced chemical equations for the following reactions. 

a) Calcium carbonate → Calcium oxide + carbon dioxide 

b) Hydrogen + chlorine → Hydrogen chloride 

c) Magnesium + hydrochloric acid → Magnesium chloride + Hydrogen 

Ans:

a) CaCO3    →   CaO  +  CO2

b) H2   +  Cl2  →   2HCl

c) Mg  +  2HCl   →   MgCl2   +  H2

23. What is neutralization? Name the acid present in the following substances. i) Curd ii)Gastric juice 

Ans:

Reaction in which an acid reacts with a base to form salt and water

i) Lactic acid

ii) Hydrochloric acid

24. Explain the formation of ionic bond between sodium and chlorine atoms. 

OR 

a) Write the chemical reactions to prove that aluminium oxide is an amphoteric oxide. 

b) How calcination differs from roasting?

Ans:

OR

a) 

★  Al2O3   +    6HCl → 2AlCl3   +  3H2O

★   Al2O3  + 2NaOH → 2NaAlO2   + H2O

b)

★ Carbonate ores are converted into oxides by heating strongly in limited air. This process is known as calcination. 

★ Sulphide ores are converted into oxides by heating strongly in the presence of excess of air. This process is known as roasting. 

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

25. a) Give reasons: 

i)  Carbon atoms neither form C4 - anion nor form C4+ cation. 

ii) Ethanoic acid known as glacial acetic acid.  

b) Write the structural formula of the following carbon compounds: i)  Butyne ii) Cyclohexane 

OR 

a) Explain the mechanism of cleansing action of soaps. 

b) Write the differences between saturated and unsaturated carbon compounds.

Ans:

a)

i)   

★ 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.

ii)

The melting point of pure ethanoic acid is very low / 290 K and hence it freezes during winter / in cold climates. 

b)

i)

ii)

OR

a) 

★ 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 micells. 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.

b)

                 PART - C BIOLOGY        

XI. Multiple Choice Questions: 3× 1 = 3 

26. The process of producing new individuals in rhizopus is 

(A)    spore formation  (B) fragmentation 

(C) budding                   (D) regeneration 

Ans: (A) spore formation

27. Part of flower that develops into fruit and part of the seed that develops into root respectively are 

(A)  Ovary and Plumule 

(B) Plumule and radicle 

(C)  Ovary and radicle 

(D) Ovary and ovule

Ans: (C) Ovary and radicle 

28. Organisms that reproduce sexually are more likely to survive in their environment. Because in sexual reproduction these organisms, 

(A)    do not produce any variations. 

(B) will not have any errors during DNA replication. 

(C) will have the same body structure in all generations. 

(D) will have the maximum number of successful variations in the subsequent generations. 

Ans: (D) will have the maximum number of successful variations in the subsequent generations. 

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

 

29. What is the function of synapse?

Ans:

It transmits chemical signals generated at the axon terminal to the dendrite

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

Ans:

No, For self-pollination to occur, a flower must have both stamens (male part) and pistil/carpel (female part).

31. The respiration rate of aquatic animals is faster than that is found in terrestrial animals. Why?

Ans:

Because the amount of dissolved oxygen is fairly low as compared to the amount of oxygen in the air, the rate of breathing in aquatic organisms is much faster than that seen in terrestrial organisms. 

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

32. What is geotropism? Name the plant part that is positively geotropic. 

OR 

Name the hormones that perform the following functions in humans. 

i) Controlling the level of sugar in the blood. 

ii) Preparing the body to face the emergency situation. 

Ans:

★ The growth movement of a plant part in response to the force of gravity.

★ The root

OR

i) Insulin

ii) adrenaline

33. The approximate lengths of the small intestine of the animals A and B are given in the below table. Observe the data in the table and answer the question.  

Identify the herbivorous and carnivorous animal among A and B. Support your conclusion. 

Ans:

★ Animal X is herbivorous and animal Y is carnivorous.

★Because herbivores consume plant which is full of cellulose and the digestion of cellulose takes a long time. Herbivores need a longer small intestine to allow cellulose to be digested.

★ Whereas Meat is easier to digest, hence carnivores have shorter small intestine.

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

34. a) Define the following: 

i)  Food chain 

ii) Biomagnification 

b) Mention the function of ozone. Name the chemical responsible for ozone depletion.  

Ans:

a)

i) It is the sequence of organisms through which energy is transferred from one trophic level to the next,

ii) It is the phenomenon where the concentration of a non-biodegradable  progressively increases at successive trophic levels in a food chain

b) 

★ Ozone protects the earth from harmful UV-radiation 

★ CFC‘s are responsible for the decrease in the amount of ozone layer.

35. a) A short pea plant (tt) is crossed with a tall pea plant (TT). Express the result obtained in the F2 generation with the help of checkerboard. 

b) How is the baby girl sex will be determined? 

 OR 

Round and yellow seeds (RrYy) producing pea plants are self-pollinated. Express the result obtained in this crossing with the help of a checkerboard. Mention the types of the plants obtained. 

Ans:

a)

b)

★ male has one X and one Y chromosome (XY).

★ The female produces only one type of gamete (ovum) with an X chromosome.

★ A child who inherits X chromosome from her father will be a baby girl.

OR

The plants obtained are

Round yellow — 9 ,

Wrinkled yellow — 3 ,

Round green — 3

Wrinkled green — 1

36. In a situation where we withdraw our leg when stepped on thorn unknowingly, 

i)  Write the sequences of events that occur to give the response in this situation. 

ii) Which part of human nervous system controls this action?

Ans:

i) 

★ Receptors receive the stimulus of pain

★Messages reach spinal cord through sensory neuron.

★Responses reach motor neuron through association neuron.

★Responses reach effectors through motor neuron.

★ Muscles withdraw the leg.

ii) Spinal cord controls this action  

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

37. Draw the diagram showing the structure of the human heart. Label the following parts: i)  Superior vena cava ii) Left ventricle 

Ans:

XVII. Answer the following question :1x5= 5 

38. a) What happens if egg does not fertilize in human female reproductive system? Explain briefly. 

b) List any four advantages of vegetative propagation. 

c) Write two examples for the organisms that reproduce by binary fission.  

OR 

a) In women, how does a fertilized egg develop into an embryo in the uterus? 

b) Is surgical contraception a better method of contraception than physical contraception? Justify your answer. 

c) Write the function of testes in human male reproductive system. 

Ans:

a)

★Uterus prepares itself every month to receive fertilized egg. It makes its inner layer thick and spongy.

★ If fertilization doesn‘t occur the lining slowly breaks and comes out through the vagina as blood and mucous. ( Menstruation occurs )

b)

★Good qualities of a variety can be maintained indefinitely.

★Vegetative propagation gives a genetically uniform population.

★ Plants raised by vegetative propagation can bear flowers and fruits earlier.

★ This makes the propagation of plants that have lost the capacity to produce seeds 

c)

★ Amoeba

​

★ Paramecium 

★ Leishmania      (Any two)

OR

a)

★ The fertilized egg starts dividing and forms a ball of cells or embryo.

★ The embryo is implanted in the lining of the uterus where they continue to grow and develop organs to become foetus.

b)

★ Yes

★Surgical contraception more effective and permanent than physical (barrier) methods like condoms or diaphragms

c) They produce sperms and testosterone hormone which is responsible for male characters.

 

   

 

 

  

    

      

          

 

KSEEB - 10 SCIENCE - MODEL QUESTION PAPER - 3 - KEY ANSWER

      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 

(C) Convex 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 

(C) resistance      (D) power 

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? 

OR 

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.

OR

a)

★ Silver is the better conductor.

★ It has lower resistivity.

b) 

★ 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? 

 OR 

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.

OR

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? 

OR 

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:

a)

★ 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)

b)

★ 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. 

OR

a)

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. 

b)

★ 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

OR  

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.

b)

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.

OR

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

b)

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

c)

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:

a)

b)

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 

 (C) CaCO3         (D) CaOCl2

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 

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

(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. /

OR

★ 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. 

OR

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

b) 

★ Change in state

★ Change in colour

★ Evolution of a gas

★ Change in temperature

OR

a) to satisfy the Law of Conservation of Mass.

b) 

★ 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:

a)

b)

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 

(C) Preparation of food 

(D) Establishing osmotic pressure

Ans: (A) Exchange of gases 

27. The plant hormone responsible for phototropism in plants is 

(A) Auxin 

(B) Cytokinin 

(C) Abscisic acid 

(D) Gibberellin

Ans: (A) Auxin 

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

(A) Gonorrhoea      (B) AIDS 

(C) Hepatitis B        (D) Warts

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.

b)

(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.

b)

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. 

OR 

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

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

Ans:

a)

★ 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. 

b)

★ 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)

OR

a)

★ 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? 

OR 

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:

a) 

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. 

b)

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

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

OR

a)

★ 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. 

b)

Testis:

★ Production of sperms / male gametes.

★ Controls the production of testosterone. 

Seminal vesicle:

★ They add their secretion to make the sperm transport easier and provide nutrition.