KSEEB - 10 SCIENCE - MODEL QUESTION PAPER - 1 - KEY ANSWER

      KSEEB - 10 SCIENCE     

    MODEL QUESTION PAPER - 1  25-26   

     KEY ANSWER   

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.              2 × 1 = 2 

1. The S I unit of potential difference is 

(A) volt (V) 

(B) ampere (A) 

(C) coulomb (C) 

(D) ohm meter (Ωm) 

Ans: (A) volt (V)

2. The reciprocal of focal length of lens is 

(A) the power of lens 

(B)  the radius of curvature of lens 

(C) equal to the sum of object distance and image distance 

(D) equal to the difference between the object distance and image distance 

Ans: (A) the power of lens 

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

3. Write the symbols of the following components used in the electric circuit. (i) Dry cell (ii)  Rheostat 

Ans: 

4. Observe the below figure. When switch is closed, does the B end of the solenoid attract the N end of the bar magnet? Clarify the answer. 

Ans: 

★ No, the B end of the solenoid will repel the N end of the bar magnet.

★ When the switch is closed, the current flows, and the solenoid acts as an electromagnet. The Right-Hand Thumb Rule can be used to determine the polarity.

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

5. What precautionary measures have to be taken to avoid overload in domestic 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) 

6. Mention the factors on which resistance of a conductor depend. 

Ans:

★ Length of a conductor

★ Area of cross-section of a conductor

★ Nature of the material 

★ Temperature.   (Any two)

7. Observe the figure given below. Name the angle of deviation and identify its value. 

Ans:

★ the angle of deviation is angle HGF

★ its value is 38^o

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

8. a) Mention any two symptoms of myopic eye. How can this defect be rectified? 

b) What is power of accommodation of eye? 

Ans:

a)

★ Unable to see distant objects clearly

★ The image of a distant object is formed in front of the retina

★ Rectified by using concave lenses

b) The ability of the eye lens to adjust its focal length to see objects clearly at different distances.

9. Explain an activity of obtaining magnetic field lines around a bar magnet using a compass needle. 

OR 

Explain experiment that shows ‘a current carrying conductor when kept in the magnetic field experiences a mechanical force.’ 

Ans:

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

★ Place the compass near the north pole of the magnet mark the position of two ends of the needle.

★ Now move the needle to a new position such that the 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. 

OR

★ 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.  

10. Draw a ray diagram to show the image formation when an object is kept beyond ‘C’ in front of a concave mirror. Mention the nature and position of the image formed. [C: Centre of curvature of mirror] 

Ans:

Nature: real and inverted

Position: Between C and F

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

11. a) Observe the below table. Which of the below listed electrical appliances consumes more energy? 

b) 2 Ω and 4 Ω resistors are connected in parallel. If 6 Ω resistor is used in place of 4 Ω, then find the difference between the difference between the total resistance obtained in both of these arrangements. 

OR

a) A 350W bread toaster is used 6 hours a day. A 250W iron box is used 4 hours a day. If these appliances are used for 30 days, then calculate the total cost of the energy consumption at the rate of Rs. 4 for 1kWh. 

b) A fan having the power 880W is connected to a source of potential difference 220V in an electric circuit. Calculate the electric current and the electric resistance of this circuit. 

Ans:

a)

TV.

P = 250W = 0.25kW

t = 4h

E = P × t 

E = 0.25 × 4 = 1kWh

Toaster.

P = 1200W = 1.2kW

t = 1h

E = P × t

E = 1.2 × 1 = 1.2kWh

→ Toaster consumes more energy.

b) 

R₁ = 2 Ω, R₂ = 4 Ω 

1/R = 1/R₁ + 1/R₂ 

= 1/2 + 1/4 =  8/6 = 1.33 Ω

If 6 Ω instead of 4 Ω:

1/ R = 1/2 + 1/6 = 12/8 = 1.5 Ω

Difference = 1.5 – 1.33 = 0.17 Ω

OR

a)

Toaster: 

P = 350W = 0.35KW

t = 6h × 30 days = 180h

E = P × t

E = 0.35kW × 180h = 63kWh

350W × 6h × 30d = 63,000 Wh = 63 kWh

Iron box: 

P = 250W = 0.25kW

t = 4h × 30d = 120h

E = P × t 

E = 0.25kW × 120h = 30kWh

Total = 63kWh + 30kWh = 93 kWh

Cost = 93 × ₹4 = ₹372

b)

Fan: 

P = 880W

V = 220V

I = P/V = 880/220 = 4 A

R = V/I = 220/4 = 55 Ω

12. a) State the laws of refraction of light. 

b) Mention any two differences between convex mirror and convex lens. 

Ans:

a)

1st Law : 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. 

2nd law : 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. 

OR 

sini/ sinr = constant. 

b)

Convex mirror:

★ Diverging mirror

★ Forms virtual, erect image

★ Used in vehicles (rear view)

Convex lens:

★ Converging lens

★ Form real and inverted image

★ Used in magnifying glass, eye lens

                 PART - B CHEMISTRY

VI. Multiple choice questions.    3 × 1 = 3 

13. The constituent metals in brass are 

(A) copper and zinc  (B) aluminium and tin   

(C) copper and tin  (D)  zinc and aluminium 

Ans: (A) copper and zinc

14. 

Analyse the experiment expressed in the above figure. The molecular formulae of the solution ‘Y’ that gives a yellow colour precipitate by reacting with KI solution and the another product that forms here respectively are.

(A) Pb(NO3)2 and KNO3   

(B) PbI2 and KNO3

(C) Pb(NO3)2 and KI

(D) Pb(NO3)2 and K2SO4  

Ans: (A) Pb(NO3)2 and KNO3

15. A property of carbon that is responsible for giving rise large molecules is 

(A) tetravalency              (B) catenation  

(C) inflammability         (D) allotropism   

Ans: (B) catenation

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

16. How do you detect a base using blue litmus paper? 

Ans: Blue litmus remains unchanged in base so, Its not possible to detect base using blue litmus paper. 

17. What are the applications of the thermite reaction? 

Ans: 

★ used to join railway tracks.

★ used to join cracked machine parts.

18. Write the structural formula of an unsaturated carbon compound containing four carbon atoms and a ketone functional group. 

Ans:

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

19. Draw the diagram of the arrangement of apparatus used to show the reaction of zinc granules with dilute sulphuric acid and label the hydrogen gas bubbles. 

Ans:

20. a) Name the salts responsible for the hardness of water? 

b) Write the name and the molecular formula of the simplest hydrocarbon. 

Ans:

a) The salts of Calcium and Magnesium.

b) Methane, CH4

21. Draw the diagram to the arrangement of the apparatus used in the electrolytic refining of copper and label cathode. 

Ans:

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

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

(i) Manganese oxide + hydrochloric acid → manganese chloride + chlorine + water 

(ii) Calcium hydroxide + carbon dioxide → calcium carbonate + water 

(iii) Zinc carbonate → zinc oxide + Carbon dioxide

OR

Convert the following chemical reactions into chemical equations. 

(i) Ammonia forms when nitrogen gas reacts with hydrogen gas. 

(ii) Sodium oxide reacts with water to form sodium hydroxide. 

(iii) By reacting with water potassium metal produces potassium hydroxide and hydrogen gas.  

Ans:

(i) MnO2 +4HCI → MnCl2 + Cl2 +2H2O. 

(ii) Ca(OH)2 + CO2 → CaCO3 + H2O

(iii) ZnCO3 → ZnO + CO2

OR

(i) N2 + 3H2 → 2NH3

(ii) Na2O + H2O → 2NaOH

(iii) 2K + 2H2O → 2KOH + H2

23. Four solutions A, B, C and D when tested with universal indicator showed pH as 5, 2, 7 and 11 respectively. Which solution 

(i) has more hydronium ions? 

(ii) is neutral? 

(iii) is the weak acid? 

Ans:

(i) B

(ii) C

(iii) A

24. a) Explain the formation of sodium chloride molecule by the transfer of electrons. 

b) What are the products obtained when aluminium metal reacts with steam? 

OR 

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

b) How is pure zinc obtained from zinc oxide?

Ans:

a)

b)  Aluminium Oxide / Al2O3 and Hydrogen gas / H2.

OR

b)

★ Pure zinc is obtained from zinc oxide by the process of reduction.

★ Zinc oxide is heated with carbon (as a reducing agent) to obtain zinc metal: /

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

25. a) Write the structures of n-butane and isobutane. 

b) What is esterification? How ethene is obtained from ethanol? 

OR 

a) Write the dot structures of nitrogen and propyne molecules. 

b) Explain the cleansing action of soap on dirt.  

Ans:

a)

b. 

★ Reaction between an acid and an alcohol to produce esters is called esterification.

★ Heating ethanol at 443 K with excess concentrated sulphuric acid results in the dehydration of ethanol to give ethene. /

OR

a)

Nitrogen molecules

Propyne molecule

b)

★ 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.

                     PART - C BIOLOGY

XI. Multiple choice questions.  3 × 1 = 3 

26. An enzyme that secretes by the pancreas to digest protein is 

(A) amylase    (B) pepsin

(C) trypsin    (D)   lipase 

Ans:  (C) trypsin

27. In a zygote there are 24 pairs of chromosomes. Then the number of chromosomes present in the gametes are  

(A) 24 pairs    (B) 48     (C) 6 pairs      (D) 24 

Ans: (D) 24 

28. Observe the figure given below. The name of the part ‘X’ and its function is 

(A)    Neuron; transmits chemicals as electrical impulses 

(B) synapse; transmits electrical signals generated at the axon terminal to the dendrite 

(C) Neuron; transmits electrical impulses as chemicals

(D) synapse; transmits chemical signals generated at the axon terminal to the dendrite

Ans:  (D) synapse; transmits chemical signals generated at the axon terminal to the dendrite

XII. Answer the following questions : 3x1=3

29. What is the importance of xylem tissue in plants?

Ans:  It is responsible for the conduction (transport) of water and dissolved minerals from the roots to the rest of the plant parts.

30. Observe the table below showing different forms of pea plants. 

Write the indicator of the trait having green seeds and flowers at the top of the stem. 

Ans:  GGaa / Ggaa

31. How is the binary fission in amoeba differs from budding in hydra? 

Ans:

Binary fission in amoeba:

★ The parent cell divides into two daughter cells

Budding in hydra:

★ A small bud develops from the parent, which detaches to form a new individual.

XII. Answer the following questions :2x2=4

32. Name the following. 

(i) Structures that prevent the collapsing of air-passage part of trachea in the humans. 

(ii) a) Nitrogenous chemicals that are separated from the blood by the kidney. 

OR

a) In which form the excess glucose is stored in plants and animals? 

b) Name the structures of the humans small intestine that absorb digested food.

Ans:

i) Rings of Cartilage

ii) Urea and Uric acid

OR

a) 

★ in plants - Starch

★ in animals - Glycogen

b) Villi

32. Why does the stem of a growing plant bend towards the light? Explain. 

OR 

Write any two differences between central nervous system and peripheral nervous system. 

Ans:

★ When light comes from one side, Auxin diffuses to the shady side of the shoot.

★ Since the shady side cells elongate more rapidly, causing the shoot to bend towards the source of light.

OR

Central nervous system

★ It consists of brain and spinal cord.

★ They receive information from all parts of the body and integrate it.

peripheral nervous system

★ It consists of cranial nerves and spinal nerves

★ They facilitates the communication between the central nervous system and the other parts of the body 

XIV. Answer the following questions :3x3=9

34. a) Ozone layer is a boon to the life on the earth. Justify.

b) The organisms of which trophic level in a food chain are most affected by biological magnification? Why? 

Ans:

a) 

★It absorbs harmful Ultra-Violet (UV) radiation coming from the sun.

★ UV radiation can cause skin cancer and damage  crops.

b)

★ it accumulates the highest concentration of the toxic substance at end of the chain.

35. Explain: 

a) The determination of the height of a plant by genes. 

b) The determination of the sex of the male child in humans.

OR 

A red flowering pea plant (RR) is crossed with a white flowering pea plant (rr). Show the result of F2 generation with the help of a checker board. Write the phenotypic ratio and the genotypic ratio of the plants obtained in F2 generation. 

Ans:

a)

★ The amount of growth hormone in plants is dependent on the efficiency of the process for making it, which involves an enzyme.

★ If the enzyme works efficiently, a lot of hormone is made, and the plant will be tall.

★ ​If the enzyme works less efficiently,  the amount of hormone will be less, and the plant will be short.

b) 

★ Father has X and Y chromosomes and mother has only XX chromosomes. 

★ The child received Y chromosome from father, also receives X chromosome from mother, then child will be boy.

OR

Phenotypic ratio: 3 : 1

Genotypic ratio : 1 : 2 : 1

36. Name the hormones that perform the following functions in humans. 

(i)  Controlling the sugar level in the blood. 

(ii) Prepare the body to deal with emergency situations. 

(iii) Controlling the fats, proteins and carbohydrates metabolism. 

Ans:

(i) Insulin

(ii) Adrenaline

(iii) Thyroxin

XV. Answer the following questions : 1x4=4 

37. Draw a diagram showing the schematic sectional view of the human heart. Label the following parts. (i)  Septum Right (ii) atrium 

Ans:

XVI.Answer the following questions :1x5=5 

38. a) List the three methods of contraception that are usually followed by human beings. 

b) What is the function of the vas deferens and prostate gland in the human male reproductive system? 

c) How does the menstrual cycle occur? Explain. 

OR 

a) Write any two differences between self and cross pollination. 

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

c) Mention any four advantages of vegetative propagation.  

Ans:

a) 

★Barrier method: Condom, diaphragm, cervical caps

★ Chemical method: oral and vaginal pills

★ Surgical method: vasectomy in males and tubectomy in females.

b)

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

★ vas deferens : Transport sperm from testis.

c) 

★ 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. 

OR

a)

Self pollination:

★Pollen transfers from an anther to the stigma of the same flower or another flower on the same plant.

★ Pollinators  not required.

Cross pollination:

★ Pollen is transferred from the anther of one plant to the stigma of another plant 

★ Pollinators not required.

b) 

★ Zygote is formed. 

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

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

c)

★ it can be used to grow plants that don't produce viable seeds, such as bananas, roses, and pineapples.

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

★ All plants produced are genetically similar to parents.

★Good qualities of a variety can be maintained indefinitely.