» Science : CBSE Sample Question Papers

All India

Section - A

1. How is the rate of reaction influenced by
(i) raising the temperature of reactants ?
(ii) adding to the reacting mixture a product of reaction without change in volume ? 1
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2. How are the molecules of aldehydes and ketones structurally different ? 1
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3. Name one non-metal and one metal which are in liquid state at room temperature. 1
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4. Name two other planets of the Solar System which are similar to the Earth in composition and structure.1
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5. How is the strength of the magnetic field at a point near a wire related to the strength of the electric current flowing in the wire ? 1
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6. How is chloride of lime chemically different from calcium chloride ? Why does chloride of lime gradually lose its chlorine when kept exposed to air ? 2
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7. What is formalin ? How does it react with Tollen’s reagent ? State any one of its uses.

OR
Complete the following reaction equations :

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8. What is a galaxy ? Name two common shapes of galaxies. Why is our galaxy called Milky War ? 2
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9. State one point of difference between a natural satellite and an artificial satellite. Name the type of orbit suitable for a geostationary satellite. 2
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10. Give one example of a nuclear fusion reaction. Describe one method for making such reactions possible. 2
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11. State Arrhenius’ concept of acids and bases. Giving reason, select a strong acid and a weak base from amongst the following substances :
H₂CO₃, HNO₃, NaOH, NH₄OH 3
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12. How is it that we can use detergents for washing clothes even when the water is hard, but not soaps ? What change has been made in the composition of detergents to make them biodegradable ?

OR
What is a polymer ? How have been polymers been classified ? Name one polymer for each of the following applications : (i) For insulating electric wires. (ii) For non-stick coatings on kitchen utensils. (iii) For blending with cotton to make shrink-resist cloth. 3
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13. Give reasons for the following :
(i) Silicon counts among metalloids.
(ii) Carbon is not used for making aluminium from aluminium oxide.
(iii) For making hydrogen by reaction with hydrochloric acid, granulated zinc is preferred to a block of zinc. 3
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14. Write chemical equations for reactions taking place when :
(i) Zinc carbonate is calcined.
(ii) Ammonia gas is passed over heated copper (II) oxide. (iii) SO₂ gas and H₂S gas are together bubbled through water. 3
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15. What are electrolytes ? Define Faraday’s constant for electrolytic reactions. Find chemical equivalents of Cu(II) (at. wt. 63.5) and Ag(I) (at. wt. 108). 3
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Delhi

Section - A

1. Draw a figure to show how the rate of a chemical reaction in general changes as the temperature of reactants is increased step-wise. 1
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2. Name the classes of organic compounds represented by the following formulae :

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3. Name any two neutral oxides. 1
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4. What type of force or forces keep the Sun and its planets in their respective places ?

OR
What force makes an apple on a tree to fall to the ground and what force makes a balloon filled with
hydrogen to rise into air ? 1
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5. How can it be shown that a magnetic field exists around a wire through which a direct electric current is passing ? 1
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6. What is the chemical name of washing soda ? Name the three chief raw materials used for making washing soda by the Solvay process. 2
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7. What is meant by ‘fermentation’ ? Write chemical equations for the two steps involved in preparing ethanol by the fermentation of molasses.

OR
Name the main products formed when :
(i) Ethanol is oxidised by an alkaline solution of KMnO₄.
(ii) Propanone and hydrogen cyanide form an addition compound.
(iii) Sodium ethanoate is heated with soda lime.
(iv) Methanal is reduced with hydrogen in the presence of finely divided palladium. 2
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8. To which galaxy does our earth belong ? How is the shape of this galaxy described ?
‘Our universe is expanding’. What does it mean ? 2
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9. In cases of artificial satellites what are ‘equatorial’ and ‘polar’ orbits ? Which type of these satellite orbitals will be suitable for collecting data for weather prediction and why ? 2
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10. Which type of nuclear process is currently used in nuclear electricity generators ? Give one example each for the substances used in this context as :
(i) coolants, (ii) moderators, and (iii) nuclear fuel. 2
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11. When will the reversible reaction,
N₂(g) + O₂(g)=2NO(g)
be said to be in equilibrium state ? Write the formula co-relating the concentration of involved substances in this equilibrium state. A reversible reaction has a very low value of its equilibrium constant. What does it signify for the rate of progress of the reaction ? 3
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12. Besides being large molecules what is the other essential similar structural character of all polymers ? Give one example each for the formation of (0 an addition polymer and (if) a condensation polymer.

OR
State the monomers used and one use each for :
(a) Neoprene, (b) Teflon and © Natural rubber. 3
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13. (a) What are strategic metals ? Give one example also.
(b) State the reason for the following behaviour of zinc metal :
On placing a piece of zinc metal in a solution of mercuric chloride it acquires a shining silvery surface but when it is placed in a solution of magnesium sulphate no change is observed. 3
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14. Write chemical equations for the reactions taking place when :
(i) A piece of calcium metal is placed in water. (ii) Ammonia gas comes in contact with hydrogen chloride gas. (iii) Sulphur is heated with concentrated H₂SO₄. 3
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15. State the formula correlating the electric current flowing in a conductor and the voltage applied across it. Also show this relationship by drawing a diagram. What would be resistance of a conductor if the current flowing through it is 0.35 ampere when the Xpotential difference across it 1.4 volt ? 3
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Section - A

1. What is the contribution of Edwin Hubble to space science ? 1
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2. What is meant by instantaneous rate of reaction ? 1
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3. What are raw materials used for manufacture of glass ? 1
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4. Name the substance used as (i) a moderator and (ii) a coolant in a nuclear reactor. 1
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5. Write structural formula of ethanoic acid. 1
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6. Write the conditions under which light undergoes total internal reflection. 2
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7. Name an alloy used in the making of permanent magnets. Give two uses of these magnets. 2
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8. What is corrosion ? Give conditions in which rusting of iron takes place. 2
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9. How is bleaching powder manufactured ? Give one use of bleaching powder. 2
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10. A 40W, 220V bulb is connected to 110V supply, find (i) Current flowing in the filament, (ii) Power consumed.

OR
A 60W, 220V bulb is connected to a 220V supply, find
(i) current (ii) Energy consumed in 1 hr. 2
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11. State two major objectives of space research programme in India also give its focal length. 3
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12. Write the nature of image formed by a plane mirror. 3
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13. Why is charcoal considered a better fuel than wood ? What are disadvantages of converted wood into charcoal ?
OR
What are amalgams ? Give two examples. Give two uses of amalgams. 3
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14. What is a fuse wire ? Name the materials used in making the fuse wire. How it is connected in the house ? How the connection differs from the normal connection used for other devices?
OR
What is solar cooker ? What is the range of temperature produced in 2-3 hours of use ? Give two
limitations and advantages. 3
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15. Discuss refraction in a glass slab and hence write the basic laws of refraction. 3
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Section - A

1. What is the wavelength range of visible light ? 1
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2. What are units of concentration ? 1
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3. What is meant by pyrex glass ? 1
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4. If the angle of incidence of a ray on a plane mirror is 30°, what is the angle of reflection ? 1
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5. What is meant by Tollen’s reagent ? Give one of its use. 1
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6. Find the power and focal length of a combination of 20 cm concave lens and 10 cm convex lens. 2
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7. What will happen to a conducting wire carrying current when placed in a magnetic field ? 2
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8. At 298 K, equilibrium concentrations of reactants and products of reaction : N₂ (g) + 3H₂(g) = 2NH₃(g)
[N₂] = 0.1 mol L^-1, [H₂] = 0.2 mol L^-1, [NH₃] = 0.3 mol I L^-1.
Calculate equilibrium constant at this temperature. 2
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9. Draw a neat labelled diagram of a simple microscope.

OR
Distinguish between Renewable and Non-renewable source of energy ? 2
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10. An object is placed at a distance of 20 cm from a concave lens of focal length 10 cm. Find the (i) Position of image and (ii) magnification. 2
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11. How is slaked lime obtained from lime ? How is lime obtained from lime stone ? Give chemical equations. 3
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12. State Fleming’s left-hand rule ? How is it different from the Fleming’s Right-hand rule ? 3
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13. Write the chemical reactions of ethanoic acid with
(i) sodium metal (ii) sodium carbonate (iii) ethanol in presence of cone. H₂SO₄ (iv) soda lime
(v) LiAlH₄ (vi) Sodium bicarbonate. 3
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14. Explain the role of (i) black surfaces, (ii) reflector and (iii) glass cover in a box type solar cooker.

OR
Name the primary colours of light ? What are complimentary colours ? Explain by subtractive way how green colour is formed from blue and yellow pigments. 3
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15. What type of detergents are biodegradable ? What is the basic structure of detergents ? Why do they work well even with hard water ? Explain cleansing action of soaps and detergents. 3
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Section - A

1. Write the full form of the following :
(i)ASLV,(ii)ISRO. 1
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2. Define molarity. 1
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3. What happens when CL₂ gas is passed over dry slaked lime ? 1
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4. What are the limitations in harnessing solar energy ? 1
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5. Which glass is used for making wind screen of automobiles ? 1
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6. Why do we need sign convention in optics ? 2
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7. What are superconductors ? Give example. 2
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8. If 20% of uranium is to release energy in a bomb of 0.10 Kg, find energy released in MeV. Given: l MeV=1.6x l0^-13 J and c= 3x 10⁸ ms^-1 2
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9. Classify the following acids and bases in the categories of weak and strong :
(i) H₂SO₄, (ii) CH₃COOH, {iii) HC1O₄, (iv) H₂CO₃. 2
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10. Give two important uses of cement. 2
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11. Show how the nature of image formed by a concave mirror differs for object placed at two positions; (i) between/and pole, (ii) between/and R. 3
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12. A1500 W electric geyser is used for 2 hours everyday. Calculate the number of units of electrical energy that will be consumed in 30 days, If one unit costs Rs. 2, find the amount of the bill ?

OR
A 150 W fan is used for 12 hours a day, a 60 W bulb is used for 8 hours a day, calculate the energy consumed in 28 days. Express it in KWh. 3
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13. What is dispersion ? How and when does it form a spectrum of light ? 3
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14. How much energy will I kg mass of wood yield on complete combustion if its calorific value is 15 kJ/g ? 3
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15. Identify the charges acquired by ebonite rod when rubbed with fur material. What is the reason for it ? Does this obey the law of conservation of charge ? 3
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Section – A

1. What is the density of mass of a typical white dwarf star ? 1
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2. What are enzymes ? Give an example. 1
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3. Write chemical name and formula of baking soda, 1
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4. Name the orbit of the satellites that help in satellite communication. 1
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5, Give chemical equation for reaction of acetone with HCN. 1
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6. Write the significance of Faraday’s Constant. 2
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7. Name some devices used to tap solar energy. Give two limitations in its use. 2
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8. Calculate pH of 0.01 M NaOH solution assuming it to be fully ionised in aqueous solution. 2
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9, A family consumes 14.5 Kg of LPG in 28 days. Calculate the average energy consumed per day if the calorific value of LPG is 55 kJ/g. 2
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10. A satellite orbits a planet in a radins ‘r’ Derive a relation for the velocity of satellite in the orbit. 2
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11. Complete the following reactions :

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12. A star of mass 100 times that of the sun has come to red giant phase. Explain the next two phases in its life. 3
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13. Write structural formula of ethanoic acid. What is common name of pure ethanoic acid ? How will you prepare it from methanol ? Give chemical reaction involved and one use of ethanoic acid.

OR
{a) What is gypsum ? What happens when gypsum is heated to 373 K ?
(b) Define ‘calorific value of a fuel’. Amongst the following fuels, which one has the highest calorific value ?
C₂H₅OH,CH₄,C₂H₂.
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14. Two resistors 2Ω and 5Ω are connected as shown in the circuit.
Find (i) current drawn from cell,

(ii) Heat produced in each resistor in 2 minutes.

OR
If 2Ω and 5Ω resistors are connected in parallel to a 10 V cell, find (i) current in each resistor, (ii) ratio of heat produced in them. 3
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15. Write the reaction that takes place in a nuclear reactor. What is meant by enrichment of fuel ? When is a nuclear reactor said to have become critical ? 3
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Section - A

1. Name any two non-renewable sources of energy. 1
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2. Write any two examples of harmful radiations emitted by the nuclear wastes ? 1
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3. What will happen to white light on entering a prism ? 1
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4. Wright Me equation for laboratory preparation of hydrogen gas. 1
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5. Win-it a wire of resistance R, length / is made into a circle, what is the resistance between two points at the end of its diameter ?

OR
Why do we use semiconductors more in electronic devices. 1
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6. How can we use solar energy to overcome energy crisis ? 2
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7. Calculate pH of the solution when hydrogen ion concentration is 1.0 x 10^{-6 M. 2
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8. What is a wind mill ? Give two advantages and disadvantages of wind mill. 2
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9. What is meant by annealing of glass ? What type of glass do we get by this process ? 2
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10. If three 60 W bulbs are used for 6 hours a day and a tube light of 40 W is used for 4 hours, calculate the cost of electricity in a month of 30 days, if the cost of 1 unit is Rs. 2.50. 2
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11. Write two examples of ‘fossil fuel’. Why are they preferred over wood ? 3
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12. Draw a labelled diagram of Alternating current generator, 3
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13. What is total internal reflection ? Relate the angle of incidence and the refractive index for total internal reflection. Write the conditions necessary for total internal reflection. 3
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14. What are constituents of bronze ? Write its two main uses. Name the common constituent of brass, bronze and german silver.

OR
What type of mixtures are separated by fractional distillation ? Name the fraction of crude oil whose boiling point is more than 350⁰C. Where is it mostly used as a fuel ? 3
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15. What is the meaning of power of a lens ? When a convex lens of focal length 10 cm and concave lens of focal length 20 cm are placed in contact, find the equivalent focal length and power.

OR
A convex lens of 10 cm focal length and a concave lens of 20 cm focal length are kept in contact, how does the combination behave. Give reason. 3
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Section - A

1. What is meant by endothermic process ? Give one example. 1
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2. Name any two elements used for fabrication of solar cells. 1
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3. Who proposed the Big-Bang theory of the origin of Universe. 1
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4. What are strong acids ? Give one example. 1
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5. What is the magnification for a plane mirror ? 1
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6. What is formula of washing soda ? 2
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7. State Coulomb’s law of electric charges ? 2
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8. What is INSAT ? What are its objectives ?

OR
Give two major objectives of ISRO ? 2
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9. Calculate pH of 0.01 M HC1 if it is fully dissociated. 2
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10. A space shuttle utilises 100 Kg of liquid hydrogen during a flight. If the calorific value of hydrogen is 150 kJ/g, how much energy did it consume ? 2
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11. What are communication satellites ? Why don’t we use moon as a communication satellite ? 3
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12. What is meant by quenching of glass ? What type of glass do we get by this process ?

OR
Which one of the following reaction equations represents combustion of carbon and why ? Give another example of combustion reaction.
(i) 2C + O₂ ——-> 2CO
(ii) C + O₂ ——> CO₂
(iii) 3C + O₂ —-> 2CO + CO₂. 3

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13. What is electro-plating ? Explain the process with a diagram. Give two real life applications of the process. 3
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14. What is the significance of Oersted’s experiment ? Draw the magnetic field created by a long conductor carrying current. 3
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15. How will you prepare hydrogen gas in laboratory ? Draw a neat and labelled diagram and write chemical reaction involved. How will you test the presence of hydrogen gas ? 3
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Section - A

1. Relate the incident and emergent angle of light in a glass slab. 1
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2. What is meant by exothermic process ? Give one example. 1
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3. What is meant by catalyst ? 1
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4. If a wire of resistance R, length / made of material of resistivity p is cut into two equal parts, find the resistivity and resistance of the two pieces. 1
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5. Define pH. 1
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6. Name two materials used in the manufacture of solar cells. What is the efficiency of modern solar cells? 2
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7. Out of the two fuels C₄H₁₀ and C₄H₉OH, which one is expected to have a higher calorific value and why? 2
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8. Draw the ray diagram to show how a simple microscope magnifies.
OR
State Faraday’s law of electrolysis. 2
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9. Give two important properties of steel. 2
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10. Equilibrium constants for the reactions given below are provided in the right hand side at 298 K.

In which case, formation of products will be more favourable ? 2
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11. What is fuse wire ? Why do we need it ? How is it connected in electric networks ? 3
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12. Write chemical equations to show what happens when :
(i) Ammonia is passed over heated copper oxide.
(ii) CO is pased over heated ferric oxide. (iii) Sulphur powder is heated with concentrated HNO₃.

OR
How will you prepare sulphur dioxide gas in the laboratory ? Draw a neat and labelled diagram and write chemical reaction involved. Give two physical properties of SO₂. 3
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13. Write the mirror formula with proper sign convention. A convex mirror u^ed on an automobilehas radius of curvature of 3.00 m. Find the position and nature of image of a bus at a distance of 5.0 m from the mirror.
OR
A concave lens of focal length 10 cm is given. An ant 2 cm long stands vertically on the principal axis at a distance of 15 cm. Find the position and nature of image formed writing the lens formula, with proper sign convention. (1/,+72+2 = 3)
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14. Define rate of reaction. Calculate the rate of reaction of ion Cis-Platin with water between t₁ =20 minutes and t₂ = 40 minutes from the following table : 3

15. Write the basic principle and working of an electric motor. 3
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Section - A

1. The refractive index of water and glass are 1.33 and 1.5 respectively. Find the refractive index of water with respect to glass. 1
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2. Give one example of slow reaction. 1
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3. What is the role of rods and cones in human eye ? 1
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4. Write reaction of methanal with HCN. 1
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5. Why do we make conductors of heating devices made of an alloy instead of a pure metal ? 1
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6. What happens when calcium hydroxide is treated with chlorine gas ? Give chemical equation. 2
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7. How much solar energy is received in 1 m area in one hour.
Given : Solar constant is 1.4 kW per square metre ? 2
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8. What are primary colours and complementary colours. Give two examples each. 2
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9. Calculate pH of a solution having [H⁺] = 1.0 x l0^-4 mol L^-1. State whether the solution is acidic or basic.

OR
N₂O₄(g)=2NO₂, the concentration of [N₂O₄] = 4.0 x 10^-2 mol L^-1; [NO₂] = 1.5 x 10^-2 mol L^-1 at equilibrium. Calculate the value of equilibrium constant, 2
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10. Who first found that current can produce magnetic field ? Write the Right hand grip rule to find the direction of magnetic field. 2
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11. A white powdered solid, when added to water produces a hissing sound. Identify the compound. How does this compound react with moist hydrogen chloride gas ? Write the chemical equation. Give two uses of same compound. 3
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12. What is the source of Geothermal energy ? Name the places where this energy is tapped. 3
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13. Metals are electropositive in nature, why ? How are most reactive metals obtained from their ore ? Name the method and give one example of such metal.

OR
What is meant by refining of petroleum ? Name the process used for refining. Give name and uses of products obtained at 180^°C and 260^°C. 3
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14. What do you mean by summer and winter solstice ? 3
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15. Docs the nature of image formed by a concave mirror depend on the position of an object ? Show this with the help of two ray diagrams. 3
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