CBSE Class 10 Science Sample Paper 6 Solutions PDF

SOLUTIONS SAMPLE PAPER - 6 SECTION - A 1. (d) It is used for cleaning iron sheets before Caution galvanisation.  In order to solve...

SOLUTIONS SAMPLE PAPER - 6 SECTION - A 1. (d) It is used for cleaning iron sheets before Caution galvanisation.  In order to solve such question, students may use Explanation: Chlorine is generally used for the exclusive method, by crossing out the incorrect sterilisation of drinking water, production of options first. For e.g., option (b) is wrong as H2O is not several important compounds like bleaching powder and for the manufacturing of plastics a suffocating gas. such as PVC (polyvinyl chloride), as well as 6. (b) (I) and (IV) paints and many more. However, hydrochloric acid (HCl) is used for cleaning iron sheets before Explanation: Mendel’s dihybrid cross is shown tin plating or galvanisation. here: 2. (c) (Parents) Explanation: When dilute hydrochloric acid is added to copper oxide, it gives green coloured (Gametes) copper chloride and water. The balanced equation for the chemical reaction taking place (F1) is given below: CuO + 2HCl(dil.) → CuCl2 + H2O 3. (d) thermal decomposition reaction TR Tr tR tr (F2) Explanation: When mercury (II) oxide is heated TR TTRR TTRr TtRR TtRr strongly, it decomposes to give the elements P P P P mercury and oxygen. Tr TTRr TTrr TtRr Ttrr 4. (d) All of these. P Q P Q Explanation: Food vacuole is the structure ‘X’, a bag like structure inside the cell of certain tR TrRR TtRr ttRR ttRr protozoan such as Amoeba where the ingested P P U U food is digested. When Amoeba completely tr TtRr Ttrr ttRr ttrr encircles food with its pseudopodia and the P Q U S tips of the pseudopodia touch each other, the membrane at that point dissolves, encapturing The plants obtained are in the ratio of the food into the cell within a bag called the 9:3:3:1 food vacuole. Tall plants with round seeds (P) = 9 Related Theory Tall plants with wrinkled seeds (Q) = 3  Food gets digested inside the food vacuole by digestive enzymes. Short plants with round seeds (U) = 3  The digested food diffuses into the cytoplasm and is Short plants with wrinkled seeds (S) = 1 utilised by the cell- Assimilation. From this cross, we can say that new  The undigested food remains in the food vacuole and combinations are formed i.e., short plants with is thrown out of the body- Egestion. round seeds and tall plants with wrinkled seeds. 5. (c) S: FeSO4; R: Fe2O3; G: SO2, SO3 7. (a) (i) Explanation: Explanation: A convex mirror always forms a virtual but diminished image of an object Green Reddish Suffocating placed anywhere in front of the mirror. A (S) brown (R) Smell concave mirror forms a virtual and magnified (G) image of an object when it is placed between (turns blue litmus its pole and focus. Therefore, we will use a Sulphurous to red) concave mirror to see an enlarged image of our acid face. Sample Paper 6 1 BUY LATEST EDUCART BOOKS ON AMAZON - https://amzn.to/4cw1M5E  CLASS 10 BOOKS h i P ra c t i c e # S a a i ! Zar o o r i H National Best-selling Publisher Books: Question Banks & Sample Papers BUY Latest Syllabus & Paper Pattern at special discount NCERT Textbooks with Solutions www.educart.co  Caution ρc ρm ⇒ =  Students usually get confused between the two types Ac Am of mirror and the nature of image formed by them. Ac ρc The ray diagram for the image formed by concave ⇒ = , mirror when object is placed between pole and focus Am ρm is drawn below: where Ac and Am are the area of cross-section of copper and manganin wires respectively. A' E A Since, ρc < ρm; Ac < Am. D Therefore, wire made of manganin will be C F B B' thicker. Y X 11. (a) 0.4 A Explanation: When devices are connected in Ray diagram for image formed by a convex mirror is parallel, the potential difference across them drawn as given: is equal but the currents are in inverse ratios of A x D their resistances. E A' Let V be the potential difference, I current across 60 W bulb and I2 across 40 W bulb. B P B' F C P = VI P ⇒ V= I 8. (b) moving slightly 60 Therefore, V= = 100 V. Explanation: The air just above the fire becomes 0.6 hotter, making it optically rarer while the colder The current I2 through 40 W bulb is: air further up is optically denser. As light passes through these layers of hot and cold air with P 40 I= = A = 0.4 A different optical densities, it undergoes random V 100 refraction. This random refraction causes the objects to appear as if they are moving slightly. 12. (a) Relative strength of magnetic field in that region. 9. (a) Explanation: The relative closeness of the magnetic field lines indicates the relative strength of the magnetic field in that region. As the magnetic field lines are diverging near the ends of a current carrying straight solenoid, Explanation: When a ray of light appears to it indicates a decrease in the strength of the pass through the focus of a convex mirror, the magnetic field near the ends of the solenoid. reflected ray will be parallel to the principal axis. Related Theory 10. (b) Manganin  Characteristics of magnetic lines of force: Explanation: The resistance R of a wire is given (1) The magnetic lines of force indicate the direction in which a N-pole would move if placed at that l point. by R = ρ where r is the resistivity of the A (2) The relative strength of the magnetic field is material of the wire, l is the length and A is the shown by the degree of closeness of the field area of cross-section of the wire. lines. Given that the lengths l and resistances R of (3) No two lines of force intersect each other, for both wires are equal, we can compare their if they did, it would mean that there would be cross-sectional areas and resistivities: two directions of magnetic field at the point of intersection. l l ρc =ρ (4) The direction of magnetic field at any point is Ac m Am found by drawing a tangent at that point. 2 Science Class X BUY LATEST EDUCART BOOKS ON AMAZON - https://amzn.to/4cw1M5E 13. (b) (A) – (iii), (B) – (i), (C) – (iv), (D) – (ii) varying amounts of insecticide and pesticide Explanation: residues. These residues cannot always be removed only by washing or other means. Due to Column I Column II this, consumption of such plants and organisms (Salt) (Use of Salt) by humans, results into the accumulation of these (A) Plaster of (iii) Makes surfaces harmful chemicals, into the body in maximum paris smooth concentration. (B) Washing soda (i) Removes perma- nent hardness of Related Theory water  As human beings are at the top of the trophic level in any food chain, maximum concentration of these (C) Bleaching (iv) Decolourisation harmful chemicals get accumulated in our bodies. powder (D) Baking soda (ii) Antacid Caution  Students usually get confused and do not know how 14. (b) 7.67 Ω biological magnification is related to food chain. Explanation: The resistances 1 Ω and 2 Ω are in parallel. Their equivalent resistance is 17. (d) (A) is false but (R) is true. 1 1 1 3 Explanation: Chips bags are flushed with inert = + = gas such as nitrogen to prevent oxidation of RP 1 2 2 fried food items or in other words, to prevent 2 ⇒ RP =Ω = 0.67 Ω chips from getting rancid. But oxygen is not an 3 inert gas and in fact will help in rapid oxidation This combination is connected in series with 4 Ω of fried food items such as chips. and 3 Ω resistances. Therefore, equivalent resistance between A and Related Theory B is (4 + 0.67 + 3) Ω or 7.67 Ω.  The condition produced by oxidation of fats and oils in 15. (a) Graphs drawn by both students A and B are foods marked by unpleasant smell and taste is called correct. rancidity. Explanation: When resistances are connected  Prevention of Rancidity: in series, their equivalent resistance is more (1) By adding anti-oxidants to foods containing than when they are connected in parallel. fats and oils: Usually substances which prevent V oxidation (antioxidants) are added to foods As Resistance = = slope of V–I graph = containing fats and oil. The two common anti- I Reciprocal of slope of I–V graph, the slope for oxidants are BHA (Butylated Hydroxy-Anisole) and BHT (Butylated Hydroxy-Toluene). resistances in series is greater than slope of resistance in parallel as correctly drawn by (2) Keeping food in air tight containers helps to slow student A. down oxidation. (3) By keeping food in a refrigerator. Similarly, slope of resistance in series is less than (4) By storing foods away from light. the slope of resistance in parallel in the graph V 1 I 18. (a) Both (A) and (R) are true, and (R) is the drawn by student B. But as R = or = , I R V correct explanation of (A). graphs drawn by both students are correct as in both graphs, resistance in series > resistance in Explanation: Bile contains bile salts, which are essential for digestion. Fats are present in parallel. the intestines in the form of larger globules 16. (a) Biomagnification of egg shells and bones which makes it difficult for enzymes to act pollutes the food grains. on them. Bile salts break them into smaller Explanation: Harmful chemicals are absorbed globules and this is called emulsification. from the soil by the plants and from the water bodies by the aquatic plants and animals. 19. (b) Both (A) and (R) are true, and (R) is not As these are non-biodegradable, they get the correct explanation of (A). accumulated progressively at each trophic level. Explanation: While it is true that autotrophs This is also the reason why our food grains such capture the solar energy and convert it into as wheat and rice, vegetables and fruits contain chemical energy, an average of 10% of the Sample Paper 6 3 BUY LATEST EDUCART BOOKS ON AMAZON - https://amzn.to/4cw1M5E  food eaten by an organism is turned into its and occur frequently. Components connected own body and made available for the next in series are connected along a single level of consumers. Since, so little energy is conductive path, so the same current flows available for the next level of consumers, food through all of the components but voltage chains generally consist of only three to four is dropped across each of the resistances. steps. In a series circuit, the sum of the voltages consumed by each individual resistance is 20. (d) (A) is false but (R) is true. equal to the source voltage. Components Explanation: Components of an electrical connected in parallel are connected along circuit or electronic circuit can be connected multiple paths so that the current can split in series, parallel, or series-parallel. The two up; the same voltage is applied to each simplest of these are called series and parallel component. SECTION - B 21. (A) Given, two resistors of 6 Ω are connected in = 1.25 × 30 parallel combination. = 37.5 V 1 1 1 2 V3 = IR3 = + = RP 6 6 6 = 1.25 × 50 RP = 3 Ω = 62.5 V A resistor of 2 Ω resistance is connected in series. 22. S. Feature Soap Detergent No. RS = 2 Ω (1) Efficiency Not Very effective R = 2 Ω + RP in hard effective = 2 Ω + 3 Ω = 5 Ω water Given, voltage in the circuit (V) = 4 V (2) Scum Scum No scum formation formation formation; So, current flowing through 4 Ω, due to the absence V 4 calcium and of reaction I= = = 0.8 A R 5 magnesium between (B) Potential difference (V’) across 2 Ω salts in hard charged ends water. and calcium V’ = R I = 2 × 0.8 = 1.6 V and magnesium OR salts. (A) To determine the total current drawn from the power supply, we need to calculate the total resistance in the circuit. As the Related Theory resistances are connected in series, the  Detergents are sodium salts of sulphonic acids or equivalent resistance is given by the sum of ammonium salts with chlorides or bromide ions. the individual resistances. Examples of synthetic detergents are: Sodium Rs = R1 + R2 + R3 = 20 + 30 + 50 = 100 Ω. n-dodecyl benzene sulphonate and Sodium V n-dodecyl sulphate. Current drawn, I = R 23. Binary fission Multiple fission 125 I= = 1.25 A (1) Two daughter cells Many daughter cells 100 are formed from the are formed from (B) The voltage drop across each resistance is splitting of the the splitting of the given by Ohm’s law V = IR. parent's cell or parent's cell or If V1, V2 and V3 are the voltage drop across nucleus. nucleus. R1, R2 and R3, then V1 = IR1 (2) It occurs during It occurs during un- = 1.25 × 20 favorable conditions. favorable conditions. = 25 V Parent cell divides Parent cell divides re- V2 = IR2 only once. peatedly. 4 Science Class X BUY LATEST EDUCART BOOKS ON AMAZON - https://amzn.to/4cw1M5E  Binary fission Multiple fission (ii) The transfer of pollen grains from the anther of a flower to the stigma of (3) Both the nucleus and First the nucleus another flower of a different plant of the cytoplasm divide divides and then it same species is termed cross-pollination. simultaneously. is surrounded by cytoplasm. 25. It is given that power of the corrective lens (4) Example: Amoeba, Example: Plasmo- P = + 1.5 D Bacteria, Euglena, dium, Sporozoans. Power of a lens is the reciprocal of its focal length etc. Algae, etc. (in metres). (Any two) 1 P= f ( in m) OR Advantages of growing plants by vegetative 1 ⇒ + 1.5 = propagation are: f (1) Plants raised by this method can bear 1 flowers and fruits earlier than those or f= m 1.5 produced from seeds. 10 (2) It is cheaper, easier and more rapid method = m = 0.667 m = 66.67 cm. of propagation in plants as compared to 15 growing plants from their seeds. The focal length of the lens = 66.67 cm (3) The traits or characters of the parent plant As the focal length is positive, the prescribed lens are preserved, that is, all plants produced will be converging lens (convex lens). are genetically similar enough to the parent plant to have all its characteristics. 26. The reaction between dilute sulphuric acid with (4) Better quality of the plants can be zinc granules is given below: maintained. Those plants which do not H2SO4 + Zn → ZnSO4 + H2(g) produce viable seeds or seeds with prolonged period of dormancy, such as banana, orange, The type of reaction is displacement reaction rose, jasmine, etc., can be propagated by this because zinc metal displaces hydrogen from the method. (Any two) acid (H2SO4) as hydrogen gas (H2) and forms a salt called zinc sulphate. 24. (A) The process shown in the given image is known as pollination. The gas evolved is hydrogen gas (a) which can (B) (i) The transfer of pollen grains from the be tested by passing it through soap solution anther of a flower to the stigma of the and then bringing a burning candle near the same flower or another flower of the soap bubbles filled with gas. Hydrogen gas will same plant is termed self-pollination. burn with a pop sound. SECTION - C 27. (A) This is a thermal decomposition reaction as (C) This is a displacement reaction as crystals of iron sulphate upon heating magnesium metal, being more reactive than decompose to form three products, namely, copper metal, displaces copper from copper iron oxide, sulphur dioxide and sulphur sulphate solution and forms magnesium trioxide. sulphate and copper metal. Since a single reactant gives two or more 28. (A) The given figure depicts the chlor-alkali than two products, it is a decomposition process. The Chlor-alkali process produces reaction. chlorine gas (Cl 2) and sodium hydroxide (B) This is a double displacement reaction in (NaOH), essential chemicals utilised in which a black precipitate of copper sulphide different industries. It is termed "Chlor- is formed along with sulphuric acid solution alkali" because "chlor" refers to chlorine when hydrogen sulphide gas is passed and "alkali" refers to the alkaline chemical through copper sulphate solution. As sodium hydroxide. exchange of ions takes place between the (B) (i) NaOH, being a strong base, reacts with reactants (copper sulphate and hydrogen a strong acid like HNO3 (nitric acid) to sulphide), it is a double displacement undergo neutralization and as a result, reaction. NaNO3 (sodium nitrate) is formed. It is a Sample Paper 6 5 BUY LATEST EDUCART BOOKS ON AMAZON - https://amzn.to/4cw1M5E  basic salt, as it is formed by the reaction system and skin is reduced due to muscle of a strong acid and a strong base. contractions around small arteries, diverting (ii)  NaOH is useful to humankind in the blood to skeletal muscles. Additionally, following ways: breathing rate increases due to diaphragm and rib muscle contractions. These responses (1)  It is used for making soaps and help the animal body prepare for various detergents. situations. (2)  It is used in the manufacturing of paper. 30. (A) P represents the pollen grain. (3) It is used for making artificial textile Q represents the male germ cell. fibres such as rayon. R represents the embryo sac. (4)  It is used in de-greasing metals, S represents the female germ cell. oil refining and making dyes and bleaches. (B) Fertilisation occurs when the male gamete present in a pollen grain fuses with the (5) It is used in purifying the bauxite female gamete or egg present in ovule. ore from which aluminium metal is When the pollen grain falls on the stigma of extracted. (Any two) the carpel, it bursts open and grows a pollen Electrolysis (C) 2NaCl(aq) + 2H2O(l)  → tube downward through the style towards the female gamete in the ovary. Here, 2NaOH(aq) + Cl2(g) + H2(g) zygote is formed which later grows into (i) Chlorine gas (X) is given off at the embryo. Zygote divides repeatedly to form anode. an embryo within the ovule. Ovule develops (ii) Sodium hydroxide (Y) solution is a thick coat and gradually forms seed. Ovary formed near the cathode. grows rapidly and ripens to form a fruit. The petals, sepals, stamens, style and stigma OR may shrivel and fall off. (A) Name: Hydrated Iron Sulphate Formula: FeSO4.7H2O 31. Human beings possess 23 pairs of chromosomes. Out of these, the 23rd pair is known as sex (B) The droplets on the inner surface of the chromosomes (XX in females and XY in males). beaker cover are water drops. These water Parents droplets are due to the condensation of water molecules lost by iron sulphate Father XY × XX Mother powder. Sperms Eggs Heat FeSO4.7H2O(s) → FeSO4(s) + 7H2O(g) (C) On adding a few drops of water to the whitish powder, the powder again turned green. This X Y X X Gametes is due to rehydration of anhydrous copper sulphate to form hydrated salt. FeSO4(s) + 7H2O(l) → FeSO4.7H2O(s) 29. (A) The hormone adrenaline is released into XX XX XY XY (o spring) a squirrel's blood when it detects danger, Daughters Sons increasing heart rate and blood flow to tissues. As a result, its cells and tissues The statistical probability of getting either a receive energy more quickly, allowing it to male or a female child is 50 : 50 as the sex of the flee dangerous situations. child is determined by what chromosome he/ she inherits from father. A child who inherits an (B) Through a regulatory mechanism known X chromosome from the father would be a girl as a feedback mechanism, the presence or (XX) while a child who inherits a Y chromosome absence of a specific hormone can control its from the father would be a boy (XY). subsequent formation. (C) Adrenaline is secreted into the blood and 32. The following figure shows the refraction of carried to various parts of the body, including light through a glass prism: the heart. It stimulates the heart to beat faster, providing more oxygen to muscles. (A) Angle of incidence – ∠i However, blood supply to the digestive (B) Angle of refraction – ∠r 6 Science Class X BUY LATEST EDUCART BOOKS ON AMAZON - https://amzn.to/4cw1M5E  (C) Angle of emergence – ∠e According to 10% law, energy available to (D) Angle of deviation – ∠D grasshopper (second trophic level) = 10% of 2000 J = 200 J Energy available to bird (third trophic level) = 10% of 200 J = 20 J (B) Food chains often only have three or four trophic levels because there isn't much energy left for the consumers at the next level. Very little usable energy is left after four trophic levels due to huge amounts 33. (A) Given that, 2000 J of energy is produced of energy loss that occurs at each step. by the producers, i.e., grass. So, the In an ecosystem, there are usually more energy available to the organism at individuals in the lower trophic levels. third trophic level, i.e., bird can be (C) (i) Grass → Grasshopper → Frog → Snake calculated as follows: (ii) Maize → Mice → Snake → Hawk SECTION - D 34. (A) Copper is more reactive than silver as it is (B) Z in the given figure denotes the impurities placed above silver in the reactivity series or anode mud. It refers to the composite of metals. collection of all the impurities settled at the bottom of anode. It is very useful as (B) When a strip of zinc metal is put in copper it can later be used to refine other metals sulphate solution, then the blue colour of mixed with impurities. copper sulphate solution fades gradually (C) (i) X: Cathode; A thin strip of the pure and red brown coating of copper is metal is connected to the negative deposited on zinc strip. terminal of the battery. Zn + CuSO4 —→ ZnSO4 + Cu Y: Anode; A thin block of the impure Zinc is more reactive than copper so it will metal is connected to the positive displace copper from its salt solution. So, terminal of the battery. displacement reaction takes place. (ii) An acidified solution of copper (C) If copper is kept open in air, it slowly loses sulphate is utilized in this process. its shining brown surface and gains a (iii) Pure metal dissolves into the green coating as it forms basic copper electrolyte and gets deposited on the carbonate, CuCO3. Copper reacts with cathode. moist carbon dioxide in the air and forms Caution green colour basic copper carbonate.  Students usually make mistakes while identifying (D) Out of Mg, Ag, Zn and Cu, Ag will be the method of extraction for different metals. The displaced from the solution of its salts by method of extraction depends on the reactivity of other three metals. Least reactive metal metals. can be displaced from its solution by 35. (A) other three metals. Silver is least reactive out of the given four metals. (E) No reaction takes place when some silver (ii) Oesophagus pieces are put into green coloured ferrous sulphate solution as silver is less reactive than iron and hence, cannot displace iron from ferrous sulphate solution. (iii) Stomach OR (iv) Small intestine (A) The metal ‘P’ is copper (Cu) and it is extracted by the process of electrolytic (iv) Large intestine refining. Metals such as copper, zinc, silver, (colon) gold, etc.; are refined electrolytically. The Alimentary Canal Sample Paper 6 7 BUY LATEST EDUCART BOOKS ON AMAZON - https://amzn.to/4cw1M5E  (B) The inner lining of the small intestine has (aluminium rod) when it is placed in a numerous finger-like projections called magnetic field. villi which increase the surface area for (ii) The direction of force acting on the rod absorption. The villi are richly supplied with will be reversed on reversing the direction blood vessels which take the absorbed food of current. The rod will now be displaced to each and every cell of the body, where it is towards the right as direction of current utilised for obtaining energy, building up new (given by central or middle finger) is tissues and repair of old tissues. reversed. OR (B) On reversing the direction of poles of the (A) Human respiratory system: magnet, the direction of magnetic field is reversed due to which direction of force exerted on the rod will also be reversed. If current is flowing from end B to A of the rod, the rod will be displaced towards right. (C) Displacement of the rod will be largest when the direction of current is at right angles to the direction of the magnetic field. OR (A) The field strength is largest at R because it is closer to the wire as the field lines are closer (B) Human beings have network of respiratory together and more dense. tubes in their lungs such as trachea is divided into bronchi. Each bronchus divides in lungs (B) If the current in the wire is reversed, the mag- netic field at R will have the same strength but to form bronchioles and bronchioles finally terminate into balloon-like structure called in opposite direction. alveoli. (C) (i) To avoid electric shocks, the metal body of The walls of alveoli contain an extensive an electrical device is earthed. A wire called network of blood-vessels and they provide a earth wire is used to connect the metal body of the electrical device to the earth, vast surface area for exchange of gases. which is at zero potential. 36. (A) (i) As the field is directed upwards, the (ii) In household circuits, we have three wires, aluminium rod is placed in such a way the live wire, the neutral wire and earth between the horseshoe magnet that the wire. One end of earth wire is connected north pole of the magnet is vertically below to the device and other end of the wire is and south pole vertically above the rod. connected to the earth. We now say that When the current is passed in the rod the device “is earthed or grounded”. Usually, from B to A, we will observe that the the three wires are connected to three-pin rod is displaced towards the left. The plug. The earth wire connection carries the displacement of the rod is due to the force current to the earth from the device and acting on the current carrying conductor prevents an electric shock. SECTION - E (C) 37. (A) The black growth is due to bread mould. Bread mould grow from tiny spores that are lost in the air. The slice of bread has provided suitable conditions like warmth, darkness and moisture for the spores to grow. (B) The organism seen on the bread is Rhizopus and the tiny thread-like structures are the hyphae of the bread mould. The mode of reproduction in Rhizopus is spore formation. Spore Formation in Rhizopus 8 Science Class X BUY LATEST EDUCART BOOKS ON AMAZON - https://amzn.to/4cw1M5E  OR (1) Alkane - CnH2n+2 (2) Alkene - CnH2n (C) The spores are covered by thick walls of tiny blob-on-a-stick like structures, (3) Alkyne - CnH2n–2 which are not reproductive parts, but 39. (A) The objective lens forms a real image of protect the spores from unfavourable the object whereas the eyepiece forms a conditions, until they come into contact virtual image of the object. with moist surface and begin to grow (B) Power of a lens is the reciprocal of its in favourable conditions. Such spores focal length. As the ratio of the focal are produced in large numbers and can lengths of the eyepiece and objective spread through air, water or animals in lenses is 10 : 1, the ratio of power of contact. They germinate when conditions eyepiece and objective lens would be are favourable. Thus, organisms like 1 : 10. Rhizopus are benefited greatly when they (C) Magnification produced by a lens is the are produced through spores. ratio of size of image (h’) to the size of object (h). It can also be written as: 38. (A) A and F belong to same homologous h' v series of alkanes. B and E belong to same m= = h u homologous series of alkenes. C and D belong to same homologous series of where u and v are the object distance and image distance respectively. alkynes. (B) B is an alkene having general formula Related Theory CnH2n, the homologous series to which E  Magnification is always positive in case of a concave belongs. lens as it always produces a virtual and erect image. (C) A and F have general formula CnH2n+2 Magnification is positive in case of a convex lens i.e., of alkanes which are saturated when the image formed is virtual and it is negative when image formed is real. hydrocarbons. C and D belong to a homologous series alkynes having general OR formula CnH2n–2. B and E are alkenes. (C) As the magnification of the objective lens is 10 and objective lens forms a real OR image of the object, m = –10. (C) 'B' is an alkene whose general formula is CnH2n. 'F' is an alkane whose general Since object distance, u = –2 cm, then formula is CnH2n+2. v using the formula m = u Caution ⇒ v = mu = (–10) (–2) = 20 cm  Students usually get confused with the general formulae of alkane, alkene and alkynes. General Therefore, the image formed is real and at formule for: a distance of 20 cm. Sample Paper 6 9 BUY LATEST EDUCART BOOKS ON AMAZON - https://amzn.to/4cw1M5E  SOLUTIONS SAMPLE PAPER - 7 SECTION - A 1. (a) Sodium reacts violently with cold water. 5. (c) Only (III) Explanation: Metals like sodium and Explanation: The rate of transpiration potassium react violently with cold water decreases with increase in humidity. It and the reaction is so exothermic that the increases linearly with increase in wind hydrogen evolved may even catch fire. speed, light intensity and temperature upto a Therefore, small pieces of sodium should not certain level and then attains saturation level. be thrown into sink in a laboratory. 6. (b) 8 Ohm-metre 2. (b) (II) Thyroid – Excess release of its hormone Explanation: Resistance R of a wire of length causes goitre l, area of cross-section A and resistivity ρ is Explanation: Pituitary gland is called master l gland because it controls the functioning given by R = ρ. A of many other endocrine glands. Thyroxine hormone secreted by the thyroid gland A Therefore, ρ =R regulates metabolism of carbohydrates, fats l and protein. Pancreas is a heterocrine gland V 200 meaning it functions as both exocrine gland Here, = R = (as it releases digestive enzymes) as well I 5 as endocrine gland (releasing hormones). V 200 == Ohm Therefore, because the pancreas releases I 5 both enzymes and hormones, it is considered = 40 Ohm an endocrine gland. ρ = R A = 40 × 2 l 10 Related Theory A 2  Human gonads (testes and ovary) perform dual R == 40 × l 10 functions: laying of gametes (in females, it is ovum and in male it is sperm) and secretion of hormones- = 8 Ohm-m testosterone in males and estrogen in females. 7. (c) (II) and (III) 3. (c) Due to strong force of attraction between Explanation: It is observed that as the object positive and negative ions. is brought closer to the principal focus from Explanation: Ionic compounds are generally infinity, the image distance also increases. crystalline solids and hard due to the strong Also, the image distance is equal to the object force of attraction between the positive and distance when object distance is 2f, where f is negative ions. They are generally brittle. the focal length of the mirror. Related Theory 8. (d) RA pours deoxygenated blood into LV and  Ionic compounds are formed by the transfer of LA pours oxygenated blood into RV. electrons from one atom to another. Explanation: RA pours deoxygenated blood Caution into RV. The LV receives oxygenated blood  Students should know that ionic compounds consist from the LA. of ions and not molecules. They have strong forces Caution of attraction between the oppositely charged ions  Students get confused with the direction of the flow and hence, are generally crystalline solids. of blood through the heart and body. They should study the topic properly to clear their concepts. 4. (b) C2H4 : C3H6 ; C4H6 : C5H8 Explanation: C2H4: The next homologue will be C3H6 as it is in the form of CnH2n. 9. (a) Live wire C4H6 : Here, it will be C5H8 as it is in the form of CnH2n–2. Neutral wire Sample Paper 7 1 BUY LATEST EDUCART BOOKS ON AMAZON - https://amzn.to/4cw1M5E  Explanation: To determine which circuit (3) By composting of biodegradable waste. shows the correct and safe positions for the (4) By recycling the non-biodegradable fuse and the switch, you should look for a waste. circuit where: (1) The fuse is placed as close as possible 14. (d) Both (II) and (IV) to the power source, ensuring that it Explanation: As the resistance is given by protects the entire circuit from over l R=ρ , where l is the length of the wire and current. A (2) The switch is positioned such that it l can safely disconnect the load from the A is the area of cross-section, R = ρ 2 πr power source. 1 This shows that R ∝ l and R ∝ 2. 10. (b) Pepsin: Produced by gastric gland; Trypsin: r  Produced by pancreas 15. (b) 80 mL Explanation: Pepsin is produced in the Explanation: 50 mL of NaOH neutralises stomach by gastric glands. It acts in an acidic 40 mL of HCl solution. medium. Trypsin is produced by the pancreas which acts in an alkaline medium. Therefore, 100 mL of NaOH will neutralise 40 Caution = ××100 100==80 80ml mL 50  Students usually make mistake and write option (a) as answer. Trypsin works in small intestine but is produced by pancreas not by small intestine. 16. (c) 4l Explanation: Let l’ be the length of the other 11. (c) (A)-(iii); (B)-(ii); (C)-(iv); (D)-(i) wire (ii) of cross-section radius 2r. As both the Explanation: Occipital lobe is situated at the wires are of same material, their resistivity back of the brain and is primarily responsible will be equal. for visual processing. The olfactory lobe, located in the frontal lobe, is responsible for l R = r for wire with cross-section r and processing different smells. The temporal A lobe, located on the sides of the brain, is length l involved in auditory processing and the l frontal lobe, is responsible for higher-order R = ρ ...(i) πr 2 functions such as decision-making and controlling voluntary movements. For wire with cross-section '2r' and length l′ l¢ 12. (c) Third R = r...(ii) p(2r )2  Explanation: (1) Grass is the producer and occupies the rl r l¢ So, = first trophic level. 2 r (2r )2 (2) Insect eats the grass, making it the primary consumer and occupying the l′ = 4l second trophic level. (3) Frog eats the insect, making it the 17. (b) Both (A) and (R) are true, and (R) is not the secondary consumer and occupying the correct explanation of (A). third trophic level. Explanation: Concave mirrors are used as (4) Snake eats the frog, making it the reflectors because when a lighted bulb is tertiary consumer and occupying the placed at the focus of a concave mirror, then fourth trophic level. the concave mirror produces a powerful 13. (d) (II) and (IV) beam of parallel light rays. This helps us see things upto a considerable distance in the Explanation: Some ways to reduce the darkness of night. problem of waste disposal are as follows: (1) By proper segregation of waste before 18. (d) (A) is false but (R) is true. disposing off. Explanation: The current in each of the (2) By usage of more biodegradable waste. solenoid's turns are parallel and flow in the 2 Science Class X BUY LATEST EDUCART BOOKS ON AMAZON - https://amzn.to/4cw1M5E  same direction when the solenoid is operating. external magnetic fields, leading to forces The turns of the solenoid will attract each that affect the motion of the charge. In other because the currents flowing through contrast, a stationary charge does not create parallel wires in the same direction cause a a magnetic field and thus, does not interact force of attraction between them. As a result, with external magnetic fields in the same the solenoid tends to contract. way. Caution  Students should remember that in a solenoid, 20. (c) (A) is true but (R) is false. current in adjacent turns of solenoid flows in the Explanation: Inheritance from the previous same direction. Hence, the turns of the solenoid generation provides both a common body attract each other and the solenoid contracts. design and subtle changes in it due to 19. (a) Both (A) and (R) are true, and (R) is the inaccuracies during DNA copying. However, correct explanation of (A). greater diversity will be generated if sexual Explanation: A moving charge creates a reproduction is involved and not when magnetic field, which then interacts with asexual reproduction is involved. SECTION - B 21. Although in F1 generation, only the tall If danger lights were blue in colour, they would be easily scattered by the smoke, plants appear, both the traits of tallness dust and other fine particles present in the and dwarfness are inherited in the F1 plants; atmosphere due to which they would not be but as the tallness trait is dominant, it is seen at a distance. expressed, whereas dwarfness trait being recessive is not expressed. It is expressed in F2 24. S. Feature Xylem Phloem generation. No. The phenotypic ratio of tallness and (1) Function Xylem helps Phloem dwarfness in F2 generation is 3 : 1. in trans- helps in 22. The gas released is hydrogen to be precise. portation of transpor- Bring a burning matchstick close to the gas water and tation of being evolved to check if it is hydrogen; if the dissolved dissolved matchstick burns with a pop sound, hydrogen minerals products of gas is present. It demonstrates that how from roots photosyn- hydrogen gas has evolved. to leaves thesis from Reaction with NaOH: and other leaves to plant parts. other parts M + 2NaOH → M(OH)2 + H2 of plant. Reaction with HCl: (2) Direction of Upward Both up- M + 2HCl → MCl2 + H2 transport ward and 23. The given image shows scattering of light. downward The colour of the scattered light depends on OR the size of the scattering particles. (A) The organism which causes Kala-azar is Very fine particles scatter mainly light of Leishmania. It reproduces asexually by shorter wavelengths such as blue light, binary fission. while the particles of larger size scatter (B) Figure showing binary fission in light of longer wavelengths such as red Leishmania: light. OR The danger lights are red in colour as red light is least scattered by fog or smoke particles present in atmosphere due to longer wavelength of red colour. Sample Paper 7 3 BUY LATEST EDUCART BOOKS ON AMAZON - https://amzn.to/4cw1M5E  25. (A) Methanone or The smallest ketone has three carbon H atoms. There is no compound named methanone. (B) Propanone H C H 26. Example of organic compound which is present in biogas is methane (CH4). H Electron dot structure of methane (CH4): SECTION - C 27. A beam of white light falling on a glass prism Refractive index of medium 2 with respect to gets split up into seven colours as shown in n1 the diagram: medium 1 is given by n21 = n2 Therefore, refractive index of A with respect to B is given by nBA = 0.92. 28. (A) As the surface area of zinc dust has larger surface area than zinc granules, 1 ligh t 2 Red te 3 YOran Whi 4 ello ge the reaction will be comparatively 5 Gree w 6 InBlue n Glass prism 7 V digo faster and H2 gas will evolve with a iole t greater speed. (A) The colours at position marked 3 and (B) No reaction will take place as copper is 5 are yellow and blue respectively less reactive than zinc and hydrogen gas whereas the student identified them as will not evolve. blue and yellow. Hence, the statement (C) Hydrogen gas is not evolved when a made by the student is incorrect. metal reacts with nitric acid because Different colours of light bend through HNO3 is a strong oxidising agent. It different angles with respect to the oxidises H2 to produce water and itself incident ray, as they pass through the gets reduced to any of the nitrogen prism. The red light bends the least while oxides (N2O, NO or NO2). the violet bends the most. 29. (A) Digestion of food in our body is a (B) (i) Position 7 is the position of violet decomposition reaction. A decomposition colour, which corresponds to the reaction is a type of reaction in which a colour of a solution of potassium single compound breaks down into two permanganate. or more elements or a new compound. (ii) Position 1 is the position of red colour, which corresponds to the Related Theory colour of ‘danger’ or stop signal  Digestion is considered a decomposition reaction lights. because enzymes in the stomach and small intestine break down larger molecules into smaller OR molecules. The speed of light is minimum in medium D and maximum in A. (B) Rusting of iron is an oxidation reaction. Oxidation is the process which involves This is because the refractive index of a gain of oxygen or loss of hydrogen or medium is the ratio of speed of light in which involves loss of electrons during a vacuum to the speed of light in that medium. reaction. So, refractive index of a medium is inversely proportional to the speed of light. Related Theory As refractive index of D is the maximum,  Rusting of iron is considered an oxidation reaction, speed of light in D will be minimum. because iron reacts with oxygen molecules of air in the presence of moisture/water and rust is formed. Similarly, as refractive index of A is minimum, Rust consists of hydrated iron (III) oxides i.e., Fe2O3 speed of light will be maximum in A. and nH2O. 4 Science Class X BUY LATEST EDUCART BOOKS ON AMAZON - https://amzn.to/4cw1M5E  (C) Heating of manganese dioxide 31. (A) The type of seeds produced in F1 with aluminium powder is a single generation is RrYy or Round, Yellow displacement reaction. A reaction in which seeds. more reactive element displaces the less (B) The type of seeds that were in the ratio reactive element from its compound is 9 : 3 : 3 : 1 in F2 generation is given below: known as single displacement reaction. Round Yellow: 9 3MnO2(s) + 4Al(s) → 3Mn(l) + 2Al2O3(s) Round Green: 3  + Heat Wrinkled Yellow: 3 In this reaction, Al is used as reducing Wrinkled Green : 1 agent as it displaces Mn from MnO2 and (C) The cross obtained after self pollination Al metal is also more reactive than Mn of F1 progeny is as follows: metal. 30. (A) Resistors in the circuit are connected in parallel combination. (B) (i) Let I1 be the current flowing through R1 = 10 W Now, I1R1 = V V 5 I1 = = = 0.5 A R 1 10 (ii) Let I2 be the current flowing through R2 = 15 W Now, I2R2 = V V 5 I2 = = = 0.33 A R 2 15 (C) Ammeter reading will be 0.83 A, which is the sum of currents flowing through R1 and R2 as they are connected in parallel. This can also be done like this: Since resistors are connected in parallel 32. (A) First identify the waste as biodegradable 1 1 1 and non-biodegradable and use two = + R P R1 R 2 different dustbins according to being biodegradable or not. We can take blue 1 1 3+2 5 1 for non-biodegradable and green for = + = = or W 10 15 30 30 6 biodegradable. Biodegradable waste can 1 1 3+2 5 1 be composted and turned into manure = + = = or W 10 15 30 30 6 as it can be decomposed by micro- organisms easily. 1 1 3+2 5 1 = + = = or W Non-biodegradable waste should be 10 15 30 30 6 collected and disposed off at right place 30 so that it can be recycled. RP = 5 (B) Paper sheet, Bone, Metal can, Plastic bottle =6W 33. (A) The functions of kidneys are: As per Ohm's law (1) To remove nitrogenous waste from V = IR the blood. V 5 (2) To maintain salt and water balance I = = = 0.83 A R 6 in the body. Sample Paper 7 5 BUY LATEST EDUCART BOOKS ON AMAZON - https://amzn.to/4cw1M5E  (B) The filtration units present in the kidneys (1) Glucose are nephrons. (2) Amino acids (C) Substances which are selectively (3) Salts reabsorbed from nephric filtrate into the (4) Water blood are: (Any two) SECTION - D 34. (A) A — Pineal gland physical harm. It also stops the brain from B — Pituitary gland becoming overworked, which stops brain fatigue. Many animals lack the intricate C — Thyroid gland neuronal network required for thought, or D — Thymus have relatively few of them. (B) 35. (A) Meter 2: As it is connected in series with S. Involuntary Reflex Action the unknown resistor through which the No. Action current needs to be measured. (1) These involve These involve all (B) Circuit diagram: autonomic ner- parts of voluntary vous system. nervous system A though they are not under our control. (2) These involve These are V functioning of concerned with the internal the situations of Or body parts. emergency. A (C) Pain receptors Vertebra Spinal cord in skin Sensory nerve  bre V ouch! Message to brain (C) Graph: Painful stimulus Motor nerve (ii) (pin prick)  bre Muscle (i) di erence Potential Stimulus Reception Sensory nerves pain (pain reception) Central nervous system Response E ectors (remove Current (muscle) Motor nerves hand) (i) Straight line passing through origin. OR (ii) Curved line with increasing slope. A reflex action is a quick, automatic reaction OR to a stimuli. Reflex arc refers to the path travelled by nerve impulses and reactions (A) The magnitude of magnetic field inside during a reflex action. It consists of the the solenoid is directly proportional receptor, the spinal cord, the motor nerve to the number of turns per unit length (efferent), the effector (muscles or glands), of the solenoid, which we can see in and the sensory nerve (afferent). Animals electromagnet P. The number of turns have evolved reflex arc because the brain's are maximum in electromagnet P as thinking process is not fast enough for them. compared to Q, so this electromagnet The body's ability to respond quickly to will be the strongest and attract the adverse stimuli reduces the possibility of maximum number of pins. 6 Science Class X BUY LATEST EDUCART BOOKS ON AMAZON - https://amzn.to/4cw1M5E  (B) Electromagnets are used: 2NaCl(aq) + H2O(l) → NaOH(aq) + Cl2(g) + H2(g) (1) in electrical appliances like electric (X) (Y) (B) (A) bell, electric fan, etc. Chlorine gas is given off at the anode, and (2) in electric motors and generators. hydrogen gas at the cathode. Sodium hydroxide solution is formed near the cathode. (3) in radios, television, microphone, etc., The compound X is NaCl or sodium chloride, (4) in separating iron from non- magnetic material. Y is NaOH or sodium hydroxide, which is a strong base. (5) in magnetising steel bars. (Any two) Gas A is hydrogen and gas B is chlorine (C) Soft iron increases the strength of the gas, which is used in the manufacturing of electromagnet. bleaching powder. (D) Ways of increasing the strength of an electromagnet: Bleaching powder is produced by the action of chlorine on dry slaked lime [Ca(OH)2]. (1) If we increase the number of Chemical equation for formation of bleaching turns in the coil, the strength of powder is: electromagnet increases. Ca(OH)2 + Cl2 → CaOCl2 + H2O (2) If the current in the coil is increased, the strength of electromagnet OR increases. (A) The sodium compound which is also used in soda-acid fire extinguisher is Related Theory sodium hydrogencarbonate or NaHCO3.  Solenoid containing soft iron core in it acts as a Therefore, X is NaHCO3. magnet only as long as the current is flowing in the When sodium hydrogencarbonate is solenoid. The core of an electromagnet must be soft heated, it gives sodium carbonate, iron because soft iron loses all of its magnetism Na2CO3. when the current is switched off. The reaction taking place is: But if we use steel for making the core of electromagnet the steel does not lose all of 2NaHCO3 → Na2CO3 + H2O + CO2 its magnetism even after switching off electric Therefore, Y is Na2CO3. current and it becomes a permanent magnet. Sodium carbonate on crystallisation Electromagnets are better than permanent forms washing soda or Na2CO3.10H2O magnets because they can produce very strong magnetic fields and their strength can be controlled or Z. by varying the number of turns in their coils. Na2CO3 + 10H2O → Na2CO3.10H2O 36. When electricity is passed through an (B) We can obtain Y from Z by heating Y: aqueous solution of sodium chloride (called Na2CO3.10H2O → Na2CO3 + 10H2O brine), it decomposes to form sodium (C) Uses of compound Z i.e., washing soda: hydroxide. The process is called the Chlor- (1) It is used in the manufacture of alkali process because of the products sodium compounds such as borax. formed– chlor for chlorine and alkali for (2) It is used for removing permanent sodium hydroxide. hardness of water. SECTION - E 37. (A) A parabolic mirror is a type of concave reflection (in case of convex mirror). It is mirror which does not suffer from any represented by the letter F. spherical aberrations. The rays of light Pole: The centre of a spherical mirror is which are parallel to the principal axis called its pole (P). converge at a point called the principal focus, which lies in front of the mirror. OR (B) Centre of curvature is the centre of the (B) Principal focus. It is the point on the principal axis of the mirror at which the hollow sphere of glass which the mirror rays of light incident on the mirror in a is a part of. It lies in front of a concave direction parallel to the principal axis mirror and behind a convex mirror. meet after reflection (in case of concave Focal length is the distance between the mirror) or appear to diverge after pole and principal focus of the mirror. Sample Paper 7 7 BUY LATEST EDUCART BOOKS ON AMAZON - https://amzn.to/4cw1M5E  38. (A) The acid formed is sulphuric acid. (B) Valves - They ensure that blood does not The reaction involved is: flow backwards when atria or ventricles SO3 + H2O → H2SO4 + Heat contract. (B) Element ‘X’ is carbon. Carbon forms (C) Left and right Ventricles (6 and 7) have CO2 on reaction with oxygen. During thicker walls as compared to left and photosynthesis, plants take in CO2. right atria (8 and 9) because they (C) Non-metals act as oxidising agents since have to pump blood out of the heart. they can accept electrons. Magnesium, They pump blood at a higher pressure being a metal, produces basic oxide in to ensure it reaches all parts of the reaction with oxygen. body. 2Mg + O2 → 2MgO OR OR (C) (i)  (8) – Left atrium, (3) – Pulmonary (C) Carbon, nitrogen and sulphur are non- veins metals hence, they form covalent hydrides. (Any two) (ii) The separation of the right and left side of the heart is useful to 39. (A) (7) – Right ventricle, (2) – Pulmonary prevent mixing of oxygenated and arteries deoxygenated blood. 8 Science Class X BUY LATEST EDUCART BOOKS ON AMAZON - https://amzn.to/4cw1M5E