Physics - Electricity Question Bank

 

   I. Multiple Choice Questions. 

1. SI unit of Electric current

A. Ampere     (A) B. ohm (Ω) 

C. Volt             (V) D. Watt (W)

Ans: A. Ampere (A)

2. SI unit of Power

A. Ampere (A)     B. ohm(Ω) 

C. Volt (V)             D. Watt (W)

Ans: D. Watt (W)

3. The property of the conductor that opposes the flow of charges through it is called

A. electric current 

B. electric potential difference

C. electric resistance 

D. electric power

Ans: C. Electric resistance

4. Rate of flow of electric charges called

A. Electric current           B. Electric potential 

C. Electric resistance     D. Electric power

Ans: A. Electric current

5. The work done in bringing an unit charge from one point to another through conductor is called

A. electric current           B. electric potential 

C. electric resistance     D. electric power

Ans: B. Electric potential difference

6. Rate of consumption of energy is called

A. electric current 

B. electric potential difference

C. electric resistance 

D. electric power

Ans: D. Electric power

7. The symbol used to represent Electric cell

A. 

B.

C.

D.

Ans: D

8. The symbol for closed circuit in electric circuit

A.

B.

C.

D.

Ans: A

9. The symbol used to represent dry cell in a circuit

A.

B.

C.

D.

Ans: D

10. Symbol in electric circuit represents

A. resistor     B. ammeter 

C. dry cell     D. voltameter

Ans: a) resistor

11. In an electric circuit the ammeter and voltmeter are generally connected like this

A. both are connected in parallel 

B. both are connected in series

C. ammeter in series & voltmeter in parallel 

D. ammeter in parallel & voltmeter in series

Ans: c)ammeter in series &voltameter in parallel

12. Formula that is not applicable to represent ohm’s law is

A. V/I = R     B. V = IR 

C. I = V/R     D. V = I/R

Ans: D. V = I/R

13. The net resistance when 2 Ω & 4 Ω resistors are connected in series and a 4 Ω resistor is connected in parallel is

A. 2Ω     B. 2.4 Ω     C. 4 Ω     D. 10Ω

Ans: B. 2.4 Ω

14. 6 Ω the resistance of a conductor is 27Ω. If it is cut into three equal parts and connected in parallel, then its total resistance is

A. 6Ω     B. 3 Ω     C. 9 Ω     D. 27Ω

Ans: B) 3 Ω

15. The net resistance when 2 Ω & 3 Ω resistors are connected in parallel and a 2 Ω resistor is connected in series

A. 3.2 Ω     B. 2 Ω     C. 3 Ω     D. 1 Ω

Ans: A) 3.2 Ω

16. A piece of metallic wire of resistance R is cut into 3 equal parts. These parts are then connected in parallel. If the total resistance of this combination is Rl, then the value of R : Rl is

A. 1:3     B. 1:9     C. 9:1     D. 3:1 

Ans: B) 9 : 1

17. An electric circuit of 6V potential difference does the work of 24J, then the amount of charges flown

A. 2 C     B. 4 C     C. 6 C     D. 10 C

Ans: B) 4C

18. If 10C of charges flow through an electric circuit of 4V potential difference, then the amount of work done is

A. 10 J     B. 20 J     C. 40 J     D. 30 J

Ans: C) 40 J

19. An electric lamp whose resistance is 30 Ω and a conductor of 6 Ω resistance are connected in series to 9V battery as shown in the figure. The total current flowing in the circuit is

A. 4 A     B. 36 A     C. 0.25 A     D. 0.6 A

Ans: C. 0.25

20. In a conductor if the amount of electric current is 4A then the resistance is 12 Ω. If the resistance is doubled then the electric current would be

A. 2 A     B. 3 A     C. 4 A     D. 8 A

Ans: A) 2 A

21. The resistance of a conductor of length 4l is 4 Ω, if the length becomes 2l then the resistance will be

A. 0.5 Ω     B. 2 Ω     C. 4 Ω     D. 8 Ω

Ans: B) 2 Ω

22. Device used to measure the potential difference

A. Galvanometer     B. Ammeter 

C. Speedometer     D. Voltmeter

Ans: A) Voltameter

23. The formula for electric power is

A. P=I R         B. VI= P 

C. P = VR     D. VR =P

Ans: B) VI = P

24. The correct statement related to resistance is it is

A. directly proportional to potential difference but inversely proportional to current

B. inversely proportional to potential difference but directly proportional to current

C. inversely proportional to both potential difference and current

D. directly proportional to both potential difference and current

Ans: A) resistance directly proportional to potential difference but inversely proportional to current

25. The safety device used to avoid short circuit.

A. fuse             B. switch 

C. resistor       D. transistor

Ans: A) fuse

26. The formula used to measure electric current

A. E=VIt     B. E=Pt     C. E=RCt     D. E=Vt

Ans: B) E=Pt

27. A device used to change the resistance in the electric circuit is

A. Voltameter           B. Ammeter 

C. Galvanometer     D. rheostat

Ans: D. Rheostat

28. ‘Ohm’ is the SI unit of

A. Electric Charge 

B. Resistance

C. Electric Current 

D. Electric Potential Difference

Ans: B. Resistance

29. The metal used in the filament of an electric bulb is

A. Manganese      B. Tungsten 

C. Nickel                 D. Chromium

Ans: B. Tungsten

30. The SI unit of electric potential difference is

A. Volt         B. Ampere 

C. Ohm       D. Coulomb

Ans: A. Volt

31. The resistance of an electric heater coil is 110 Ω. Then electric current, that an electric heater draws from a 220 V source is, 

A. 0.5 A     B. 0.11 A     C. 2 A     D. 3 A

Ans:  C. 2 A

32. A device that is connected in series in an electric circuit is

A. Voltmeter     B. Bar Magnet 

C. Turbine         D. Ammeter

Ans: D. Ammeter

33. Observe the following table :

The best conductor of electricity among these materials is

A. N     B. M     C. K     D. L

Ans: B. M

34. The function of fuse in an electric circuit is that it

A. Reverses the direction of an electric current

B. Shows the direction of motion of the electric current

C. Measures the potential difference

D. Protects the electrical appliances

Ans: D. Protects the electrical appliances

35. The correct formula that shows the relationship between potential difference, electric current and resistance in an electric circuit is

A. I = V/ R     B. I = VR 

C. V = R I      D. R = I V

Ans: D. R = 𝑉𝐼

36. The device used to measure the rate of current in a circuit is

A. Ammeter               B. Voltmeter 

C. Galvanometer     D. Battery

Ans: A. Ammeter

37. The SI unit of resistivity is

A. ohm     B. volt 

C. watt     D. ohm-metre.

Ans: D. ohm-metre

38. Ohm's law gives the relationship between

A. potential difference and electric charge 

B. potential difference and resistance

C. electric current and potential difference 

D. electric current and electric power

Ans: C. electric current and potential difference

39. In an electric circuit to get an equivalent resistance Rs four resistors of 2 Ω each are first connected in series. Later to get an equivalent resistance of Rp the same resistors are connected in parallel. Then the ratio of Rs /Rp is

A. 16:1     B. 2:1     C. 4:1     D. 8:1

Ans: A.16:1

40. SI unit of electric charge is

A. Coulomb     B. Ampere 

C. Joule            D. Volt

Ans: A. Coulomb

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

(A) current 

(B) potential difference

(C) resistance 

(D) power

Ans: D. power

42. When three resistors of different resistance are connected in parallel, the quantity that remains the same in all the resistors is

(A) current 

(B) potential Difference

(C) resistance 

(D) resistivity

Ans: B. potential Difference

43. A correct statement related to the conductors X and Y given in the below figures is

(A) Since the cross section of the conductor X is less the flow of current is more in this conductor

(B) The cross section of conductor Y is more and hence resistance in it is more

(C) Since the cross section of the conductor X is small it has a low resistance

(D) The conductor Y has more cross section than the conductor X and hence the flow of current is more in it

Ans: D. The conductor Y has more cross section than the conductor X and hence the flow of current is more in it.

    II. One-mark Questions:

44. Two connecting wires of same length and same diameter are made up of copper and iron. Among these two which is having more resistance? Give reason.

Ans: Iron because the resistivity of iron is more compared to copper.

45. Two students A and B conduct experiment connecting R1 and R2 resistors in series and parallel and plot the graph of V-I as below. Who has plotted the graph correctly?

Ans:  Both are correct. ΔV/ΔI = R. The resistance is more in series and less in parallel.

46. How many joules does 1 unit (kWh) have?

Ans: 3.6 X 106 J

47. Define 1 ohm?

Ans: If the potential difference across the two ends is 1V & the current through it is 1A then the resistance is said to be 1Ω.

48. What is the meaning of 1 Ampere?

Ans: Flow of one coulomb of charge per second is 1 Ampere.

49. How many electrons does 1 coulomb (C) have?

Ans: 6 x 1018 electrons

50. The potential difference between two points of connecting wire is 1 volt. Define the statement.

Ans: Means that when 1 Joule of work is done to move a charge of 1 coulomb from one point to another

51. Name the devices used to measure electric current and potential difference.

Ans: Electric current - Ammeter

potential difference- Voltameter

52. What is the resistance of a conductor?

Ans: It is the property of the conductor to resist the flow of charges through it.

53. When did the resistance of a conductor becomes 1 Ω?

Ans: If the potential difference is 1V & the current through it is 1A then the resistance becomes 1 Ω.

54. Why is the nitrogen or argon gas filled inside the electric bulb?

Ans: To prolong the life of filament.

55. Name the commercial unit of electricity.

Ans: Kilo watt per hour (kwh)

56. How is fuse connected in an electric circuit?

Ans: In series.

57. What are the uses of fuse in domestic electric circuit?

Ans: Fuse melts when excess of current flows through the circuit due to heating effect of electric current ensures the safety of electric devices.

58. Why are tungsten wires used in electric bulb?

Ans: Due to its high resistivity, it is used in electric bulb.

59. Write the symbols for the following terms in electric circuit.

        i) A wire joint ii) electric bulb.

Ans:

60. Write the diagram of the symbol of resistors used in electric circuit.

Ans:

61. What is the SI unit of potential difference? Name the device used to measure the potential difference.

Ans: Volt (V), Voltameter

62. Suggest any two measures to avoid overloading in domestic circuits.

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):

63. What are the reasons for occurring 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 )

64. Write the symbols of the following components used in an electric circuit.

i) Rheostat ii) Wires crossing without joining

Ans:

65. Write the symbols of the following components used in an electric circuit.

        i) Electric cell ii) Voltameter

Ans:

66. Draw the symbol diagram of two electric cells connected in series in an electric circuit.

Ans:

67. Can an electric heater of 2kW capacity be connected to an electric circuit of 15A rating, 220V potential difference? Justify your answer. 

Ans:

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

Ans:

69. When the number of turns of a current carrying circular loop is increased by ten times what change that occurs in the magnetic field of it?

Ans:

     III. Two marks Questions:

70. What is electric circuit? Write the schematic diagram of an electric circuit comprising cell, electric bulb, ammeter & plug key.

71. In which of the below devices the electric energy is used maximum?

72. Which of the below electrical appliances consume more energy?

73. 2 Ω, 3 Ω & 4 Ω resistors are connected in parallel & then in series. In which connection does their total resistance will be less than their resistance?

74. 2 Ω and 4 Ω resistors are connected in parallel. If 6 Ω resistor is used in place of 4 Ω, find the difference of total resistance of two types of connections.

75. Resistivity of copper 1.63 x 10-8 Ωm & its cross section is 10.3 x 10-5cm3. Calculate the length of wire needed to make a coil of 10 Ω resistance.

76. Electrical resistivity of some substances at 200C is given below.

i) Among silver and copper which is the good conductor. Why?

ii) Which material is suitable for electrical heating. Why?

77. Explain the working principle of electric fuse.

78. Define electric resistance and resistivity. How are they interrelated?

79. Explain the working mechanism of an electric bulb.

80. In domestic electric circuit it is suitable to connect electrical devices in parallel. Mention two reasons for it.

81. State Joule’s law of heating. How fuse is connected in an electrical circuit. Mention the metal used in a filament of an electric bulb and the gas filled in the bulb.

82. A bulb is marked 220 V and 40 W. Calculate the current flowing through the bulb and it‘s resistance.

83. If an electrical fan consumes energy at a rate of 880W in voltage 220V, calculate the electric current and electric resistance.

84. The resistivity of manganese wire of length 1 m is 1·84 × 10-2 m at 20°C. If the diameter of the wire is 3 × 10-4 Ω m, what will be the resistance of the wire at that temperature?

85. The resistance of a metal wire of length 2 m is 28 Ω at 20°C. The cross-sectional area of the wire is 1.26 × 10⁻⁹ m².

(i) Calculate the resistivity of the metal.

(ii) Find the resistance of the same wire if its length is 3m.

86. Observe the given circuit:

Calculate the total resistance in the circuit and the total current flowing in the circuit.

87. Observe the diagram of below given electric circuit. Find the total resistance and the total current of the circuit.

88. An electric bulb with a resistance of 50 Ω is connected to 10 V battery in an electric circuit. Calculate the electric current flowing through the electric bulb and electric power of the bulb.

89. 1000 J of heat is produced each 2 seconds in a 5 Ω resistor. Find the potential difference across the resistor. 

90. A wire of given material having length ‘l’ and area of cross section ‘A’ has a resistance of 4 Ω. Find the resistance of another wire of the same material having length ½ and area of cross-section ‘2A’. 

91. Placing a fuse in domestic electric circuits is essential. Why? Explain. 

    IV. Three marks questions:

92. Find out amount of electric current flowing through below circuit.

93. The value of resistors R1, R2 & R3 are 5 Ω, 10 Ω & 30 Ω. If they are connected to dry cell of 12V potential difference. Calculate

i) Electric current flowing through each resistor

ii) Total electric current through circuit.

iii) Total resistance of entire circuit.

94. A Refrigerator of 400 Watt works 10 hrs daily; an electric fan of 80 Watt works 6 hrs daily and an electric bulb of 18 Watt glows 6 hrs daily. If the rate of per unit is 3 rupees, then what is the amount of electric bill the owner has to pay in the month of June?

95. 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, calculate the total cost if the rate is Rs. 4 for 1kWh.

96. 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?

97. Among iron, silver and nichrome which one is utilised inside an electric iron box which works on the heating effect of electric current. Justify your answer with 3 reasons.

98. A connecting wire of 20 Ω resistance is drawn to double its length. Calculate the resistance in new situation.

99. i) State ohm’s law. 

ii) List the factors on which the resistance of conductor depends.

100. State Joule’s law of heating. Explain the working of electric filament bulb.

101. The resistors R1, R2 and R3 have the values 10 Ω, 20 Ω and 60 Ω respectively, which have been parallelly connected to a battery of 24 V in an electric circuit. Then calculate the following:

i) The current flowing through each resistor

ii) The total current in the circuit

iii) The total resistance of the circuit. 

102. 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? 

    V. Four marks questions:

103. a) Name any two devices that work on the application of Joule’s law.

b) Why are the alloys like nichrome used in electrical heating devices?

104. a) A bread-toaster rated 350 W is used for 15 hours a day. An electric iron box rated 250 W is used for 5 hours a day. Calculate the cost of using these appliances for 30 days, if the cost of 1 kWh is Rs. 4.

b) In which method the resistors R1 and R2 could be connected so that the equivalent resistance of that electric circuit becomes low? What is the change in the value of current in the circuit by this type of connection? 

105. An electric heater connected to a 220 V generator draws a current of 10 A. What is the power of the electric heater? If it is used for 8 hours a day, then calculate the total cost of using it for 30 days at Rs. 5.00 per 1 kWh.

    VI. Answer the following questions. (5 Marks)

106. i) What is the meaning of the statement -The potential difference between two points is 1V?

ii) Name the device used to measure potential difference.

iii) What is resistance of a conductor?

iv) What is electric power?

v) Write three formulae used to find it.

SSLC Science Preparatory Exam - 2026 - Key Answer

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State level SSLC preparatory Exam - 1 (2026) Science - Key Answer

     PART - A (PHYSICS)     

  I. Multiple choice questions:   2×1=2

1. The SI unit of potential difference

(A) volt (B) Ampere (C) coulomb (D) ohm metre

Ans: (A) volt

2. Correct statement with respect to magnetic field in the given diagram is,

(C → Current-carrying solenoid, P and Q → Points inside the solenoid,R→ Point outside the solenoid) The magnetic field

(A) in P is more than in Q

(B) in Q is more than in P

(C) in R is more than in P and in O

(D) in P and in Q is equal.

Ans: (D) in P and in Q is equal.

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

3. In the given diagram, which angle is bigger among the angles r1, and r2? Give a reason.

Ans:

★ Angle r2 is larger.

★ Because light speeds up and bends away from the normal line when exiting the glass into the air.

4. Write the diagrams of the symbols of the following components used in an electric circuit:

i) Rheostat or variable resistance

ii) Wire crossing without joining.

Ans:

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

5. Observe the below given diagram of the human eye. Name the eye defect indicated in this diagram and mention the lens used to correct this defect.

Ans:

★ Myopia / Near sightedness

★ Concave lens

6. Observe the given diagram and calculate the total resistance in the given electric circuit.

Ans:

Rs = R1 + R2 + R3

Rs = 15Ω + 5Ω + 5Ω = 25

Rs = R4 + R5

Rs = 20Ω + 30Ω = 50Ω

R6 = 25ΩΩ

Total resistance:

1/ Rp = 1/25Ω + 1/50Ω + 1/25Ω

Rp = 10Ω

7. Mention any four properties of magnetic field lines.

Ans:

★ Magnetic field lines have both magnitude and direction. 

★ Magnetic field lines emerge from north pole and merge into south pole. 

★ Are closed curves. 

★ Magnetic field lines do not intersect each other. 

★ Magnetic field is strong wherever the density of field lines is more./Magnetic field lines are closely packed where the field is strong.    (Any four)

OR

What precautionary measures have to be taken to avoid overload in domestic electric circuit?

Ans:

★ Fuse should be used in the electric circuit 

★ Should avoid the direct contact of live wire and neutral wire. 

★ Avoid the damage of insulation of wires 

★ Should repair any faults in the electrical appliances 

★ Should not connect too many appliances to a single socket. (Any four)

  IV. Answer the following questions: 3x3=9

8. Explain the activity of drawing magnetic field lines around a bar magnet using a compass needle.

Ans:

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

 

★ Place the compass needle near the North pole of the magnet. Its South pole turns towards the North pole. The North pole of the compass needle is directed away from 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 its South pole occupies the position previously occupied by its North pole.  

★ 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 smooth curve. This curve represents a field line.  

★ If two field lines cross each other, it would mean that at the point of intersection, the compass needle would point towards two directions, which is not possible. 

9. Draw the ray diagram for the image formation when an object is placed between 2F1 and F1 of a convex lens. Mention the nature of the image formed. [ F1 : Principal focus of the lens. ]

Ans:

Nature of the image : Real and Inverted

10. Explain the phenomenon of formation of the rainbow in the atmosphere.

Ans:

★ Rainbow is caused by the dispersion of sunlight by tiny water droplets present in the atmosphere.

★ The water droplets act like small prisms; they refract and disperse the incident sunlight. then reflect it internally and finally refract it again when it comes out of the raindrop.

★ Due to the dispersion of light and internal reflection, different colours reach the observer’s eye.

OR

Explain Newton’s experiment that shows the recombination of spectrum of white light.

Ans:

★ Newton used a glass prism to obtain the spectrum of white light. 

★ When he placed a second identical prism in an inverted position with respect to the first prism and allowed the spectrum to pass through it, a beam of white light emerges. 

★ This shows the recombination of spectrum of white light.

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

11. a) What is magnification? If the magnification of an image produced by a lens is + 2, then mention the type of the lens.

b) The refractive index of medium A is less than that of medium B. Which of these media is optically denser ? In which of these media the speed of light is more ? 

Ans:

a)

★ Magnification is the ratio of the size of an image to the size of an object.

★ Convex lens

b)

★ Medium B is denser medium

★  Medium A 

OR

a) What is centre of curvature of a spherical mirror ? Write any two uses of concave mirror.

b) State the laws of refraction of light.

Ans:

a)

★ The centre of the sphere from which the mirror is a part.

Uses of concave mirror :

★ To obtain a parallel beam of light in torches

★ Shaving mirror.

★ Dentists use concave mirror to obtain a large image of the teeth.

★ Used in solar furnaces to concentrate sunrays

b)

Laws of refraction of light : 

★ 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. /

sini / sinr = constant. 

12. a) List the factors on which the resistance of a conductor depends.

b) Write the mathematical form of Joule’s law of heating. Name any two devices that work on the basis of Joule’s law of heating.

Ans :

a)

★ its length

★ Area of cross section

★ Nature of the conductor

★ Temperature

b)

★ H = I2Rt

The devices that work on this law are

★ Electric Toaster

★ Electric Oven

★ Electric Kettle

★ Electric Bulb

★ Electric Fuse       ( Any two )

     PART - B (CHEMISTRY)     

   VI. Multiple choice questions:  2 x 4=8

13. The type of chemical reaction in which reactants exchange their ions is

(A) Double displacement

(B) Displacement

(C) Decomposition

(D) Combination

Ans: (A) Double displacement

14. The green coloured compound that is formed when copper reacts with carbon dioxide of the moist air is

(A) Copper carbonate

(B) copper sulphide

(C) copper nitrate

(D) copper oxide

Ans: (A) Copper carbonate

15. The property of carbon that is responsible for producing large molecules is

(A) Tetravalency     (B)  Catenation

(C) inflammability  (D) Allotropism

Ans:  (B)  Catenation

   VII. Answer the following questions: 3x1=3

16. The pH values of four solutions are given in the following table. In these

a) Which solution has more concentration of H+ ions?

b) Name the neutral solution.

Ans:

a) Solution Q

b) Solution P

17. What is the importance of hydrogenation of carbon compounds ?

Ans:

★ Unsaturated carbon compounds can be converted into saturated

carbon compounds.

★ More reactive fats can be converted into less reactive fats.

★ The shelf life of carbon compounds (fatty acids) can be increased. (Any two)

18. Magnesium and Manganese metals are reacted with a strong oxidising acid. With which of these metals is the evolution of gas bubbles faster?

Ans: Magnesium.

   VIII. Answer the following questions : 3x2=6 

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

Ans:

20. Give reasons :

i) Covalent compounds have low melting points and boiling points. 

ii) Carbon does not form either C4 − or C4 + ions.

Ans:

i) because they are held together by weak intermolecular forces

ii) 

★ 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.

21. Draw the diagram of the arrangement of the apparatus used to show the action of steam on metal.

Ans:

   IX. Answer the following questions : 3x3=9 

22. Balance the following chemical equations :

i) AgC l → Ag + Cl2

ii) Fe + H2O → Fe3O4+H2

iii) N2 + H2 → NH3

Ans:

i) 2AgCl → 2Ag + Cl2

ii) 3Fe + 4H2O → Fe3O4 + 4H2

iii) N2 + 3H2 → 2NH3

OR

i) What are redox reactions ?

ii) CuO + H 2 → Cu + H 2 O. Identify the substance oxidised and the substance reduced in this equation.

iii) What is the difference between endothermic and exothermic reactions?

Ans:

i) A chemical reaction in which one reactant gets oxidised while the other gets reduced is called redox reaction.

ii) CuO is Reduced, H2 is Oxidised

iii)

★ Endothermic reaction : Reactions in which heat is absorbed

★ Exothermic reaction: Reactions in which heat is liberated

23. Explain the formation of sodium chloride molecule by the transfer of electrons.

OR

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

b) How calcination process differs from roasting?

Ans :

a) Aluminium oxide reacts both acid and base to give salt and water.

b)

★ Calcination: Carbonate ores are converted into oxides by heating strongly in limited air.

★ Roasting : Sulphide ores are converted into oxides by heating strongly in the presence of excess of air.

24. a) What is acid rain?

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

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

Ans :

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

b) Carbon dioxide

c) 

★ Sodium hydrogen carbonates/ Sodium bicarbonate

★ NaHCO3

   X. Answer the following question : 1x4=4

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

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

Ans :

b) 

★Alcohol and carboxylic acid react to form an ester. The reaction is called esterification reaction.

★ When ethanol is heated at 443 K with excess concentrated sulphuric acid, ethanol undergoes dehydration to form ethene.

OR

a) Write the electron dot structure of nitrogen and methane molecules.

b) Explain the cleaning action of soap.

Ans:

a)

Nitrogen:

Methane:

b)

★ The molecule of soaps are sodium or potassium salts of long chain carboxylic acids. 

★ Ionic end of soap interacts with water while the carbon chain interacts with oil

★ Soap molecule thus forms a structure called micelle. This forms an emulsion in water. 

★ The micelles thus help in pulling out the dirt in water.

     PART - C (BIOLOGY)     

   XI. Multiple choice questions.    3×1 = 3

26. The process of producing the new progenies in rhizopus is

(A) spore formation

(B  vegetative propagation

(C) binary fission

(D) regeneration

Ans : A) spore formation

27. An incorrect statement related to the transpiration among the following is ;this process

(A) Creates osmotic pressure for the movement of food molecules

(B) Helps in the absorption and movement of salts from the roots

(C) Creates suction force for the movement of water molecules

(D) Balances water level in a plant body

Ans: (A) Creates osmotic pressure for the movement of food molecules

28. the sequential stages that occur in the sexual reproduction of flowering plants are

(A) pollination, fertilization, seed, embryo

(B) seed, embryo, fertilization, pollination

(C) embryo, seed, pollination, fertilization

(D) pollination, fertilization, embryo, seed

Ans : (D) pollination, fertilization, embryo, seed

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

29. Draw the diagram to show the structure of open stomata.

Ans:

30. How is the sex of a male child determined in humans?

Ans: If zygote received Y chromosome from the father then the zygote develops into a male child.

31. Observe the tropisms of plants expressed in the following figures A and B. What is the difference between the movements of these plants?

Ans:

Plant A : Nastic moment

Plant B : Trophic moment

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

32. What are the differences between arteries and veins ?

Ans:

Arteries:

★ Arteries carry blood away from the heart to various organs of the body.

★ are thick walled blood vessels

★ Veins have no valves

Veins:

★ Veins carry the blood from different organs and bring it back to the heart

★ are thin walled blood vessels

★ Veins have valves           (Any two)

OR

Write the differences between aerobic respiration and anaerobic respiration.

Ans:

Aerobic respiration 

★  It takes place in the presence of O2 

★  Energy released is more 

★  Produce carbon dioxide, water, and energy 

Anaerobic respiration

★  It takes place in the absence of O2. 

★  Energy released is less

★  Produce ethanol, carbon dioxide and energy.   (Any two)

33. We pull out our foot back when we step on a thorn without realizing. Write the sequence of the events that occur in this process.

Ans :

Receptors in skin/ Receptors → sensory neuron → spinal cord → relay neuron → motor neuron → muscle in leg / effector.

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

34. Draw the diagram to show the structure of human brain and label the following parts : i) Cerebrum ii) Hypothalamus.

Ans:

35. A pure tall pea plant ( TT ) is crossed with a pure dwarf pea plant ( tt ). Express the result obtained in F2 generation with the help of checker board and mention the ratio of the types of plants.

Ans:

Phenotypic ratio : 3 : 1

3 : Tall plants

1 : dwarf plants

36. grass → Grasshopper → Frog → Snake : In this food chain.

i) Which organism has more deposition of harmful chemicals?

ii) Does the energy from the frog return to the grass-hopper? Clarify your answer.

Ans:

i) Snake

ii) 

★  No

★  The flow of energy in the food chain is unidirectional.

OR

Give reasons :

a) Production of CFC free refrigerators is compulsory.

b) Plastics remain for long period in the environment.

Ans:

a) CFC’s are responsible for the decrease in the amount of ozone layer

b) 

★ Plastics are non – biodegradable 

★ It cannot be degraded by microbes.

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

37. a) What t is emulsification of fats?

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

Ans :

a) The process of breakdown of larger fat droplets into smaller droplets of fat with the help of bile salts present in bile juice

b) 

Event occurs during photosynthesis

★ Absorption of light energy by chlorophyll.

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

★ Reduction of carbon dioxide to carbohydrates.

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

38. a) Explain the process of development of an egg into a foetus in human female reproductive system.

b) What are sexually transmitted diseases? Write any two examples.

Ans :

a)

★ The zygote divides and becomes an embryo.

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

★ The embryo continues to grow and develop organs to become foetus.

b) 

★ The disease caused by unsafe sexual contact.

★ Bacterial: Gonorrhoea and syphilis

★ Viral: Warts and HIV-AIDS

OR

a) What is asexual reproduction? What are the differences between fragmentation and fission?

b) Mention the advantages of vegetative propagation.

Ans : 

a) 

★ New individual produced by single parent / Production of young ones without fusion of gametes. 

Fragmentation

 ★The organism breaks-up into smaller pieces upon maturation, each piece develops into new individual

★ E.g., Spirogyra

Fission

★ The parent cell divides into two or more daughter cells.

★ E.g., Amoeba

b) 

Advantages 

★ Plants are genetically similar to the parent plant.

★ 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.

(Any two)

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