CLASS-10 SAMPLE PAPERS

Q1. An element ‘X’ on reaction with dilute acid evolves a gas that burns with a pop sound, while a compound ‘Y’ on reaction with dilute acid evolves a gas that turns lime water milky. Identify X and Y.

Q2. Give an example of a metal which is the best conductor of heat.

Q3. Why is CNG considered an environmental friendly fuel ?

Q4. When a metal X is treated with cold water, it gives a basic salt Y with molecular formula XOH (Molecular mass = 40) and liberates a gas Z which easily catches fire. Identify X, Y, Z.

Q5. It is advised to pour acid into water rather than water to acid for the dilution of acids. Why ?

Q7. Write the balanced equation for the following reaction and identify the type of reaction in each case.

1. Potassium bromide (aq) + Barium iodide (aq) → Potassium iodide (aq) + Barium bromide(s)
2. Hydrogen(g) + Chlorine(g) → Hydrogen chloride(g)

Q8.

1. Balance the chemical equation : Fe(s) + H₂O(g) → Fe ₃O4(s) + H₂(g)
2. Identify the type of reaction in the equation given below. Na₂SO₄(aq) + BaCl₂(aq) → BaSO₄(s) + NaCl(aq)

Q9. What are the final products of carbohydrates,proteins and fats after their digestion.

Q14. Explain why :

1. Respiration is an exothermic reaction,
2. All decomposition reactions are endothermic reactions.
3. When blue salt of copper sulphate is heated it becomes colourless?

Q15. What is Baking soda chemically called ?Give reaction involved in its preparation. Write one of its uses.

Q16. A gas is produced when conc. H2SO4 is added to solid sodium chloride taken in a test tube. The gas coming out through the delivery tube is passed over a dry blue litmus paper and then over a moist blue litmus paper. What would you observe?Explain reason with the help of chemical equation.

Q17.

1. Define tropic movement.
2. Why do multicellular organisms need another means of communication between cells besides nervous co-ordination ?

Q18. Name the hormone synthesised at the shoot tips. How does it help the plant to respond to light ?

Q23.

1. Give two methods to prevent the rusting of iron?
2. Name the ores of the following metals
   1. mercury and
   2. zinc
3. Explain, with the help of a diagram, how impure copper metal can be refined? Label the important arrangements in the experimental set up.

Q24.

1. Draw a neat diagram of human excretory system and label the parts that : (i) produces urine (ii) releases urine to outside.
2. What are the end products of digestion of fat and protein in human beings ?

Q26. Four students were given three colorless liquids A,B,C of water, lemon juice and a mixture of water and lemon juice respectively. After testing these liquids with pH paper, following sequences in colour change of pH paper were reported.

1. Blue, Red and Green
2. Orange, Green and Green
3. Green, Red and Red
4. Red, Red and Green The correct sequence of colors observed is :
   1. (i)
   2. (ii)
   3. (iii)
   4. (iv)

Q27. Four students (A), (B), (C) and (D) separately measured the pH values of each one of the given samples of distilled water, acetic acid, dilute hydrochloric acid, and a solution of sodium hydroxide using pH papers. Which one of the following represents a correct measurement?

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

Student	Water	Acetic acid	Hydrochloric acid	Sodium Hydroxide
(a)	7	1	1	1
(b)	7	3	1	1
(c)	7	1	1	13
(d)	7	3	1	13

Q28. Four students performed the reactions of a dil. hydrochloric acid and a solution of sodium hydroxide with zinc metal and solid sodium carbonate separately. They reported the possible reaction by (ü) and no reaction by (X). In which of the following sets all observations are correct?

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

Set	HCL + Zn	HCL + Na₂CO₃	NaOH + Zn	NaOH + Na₂CO₃
(A)
(B)
(C)
(D)

Q29. A student added some copper sulphate crystals in water in a beaker and observed the colour of the solution obtained. The colour of the solution observed by him must be :

1. green
2. blue
3. yellow
4. pink

Q30. When crystals of FeSO4 are strongly heated the residue obtained is

1. red in colour
2. blue in colour.
3. green in colour.
4. colourless.

Q36. To determine that light is essential for photosynthesis, following are the steps but not in correct sequence :

1. Pluck the leaf and do the starch test.
2. Keep the selected plant in sunlight.
3. De-starch the plant for 48 - 72 hours.
4. Cover the leaf with black paper strip.

   The correct sequence is

   1. (iii), (i), (ii), (iv)
   2. (iii), (ii), (iv), (i)
   3. (iii), (iv), (ii), (i)
   4. (i), (ii), (iv), (iii)

Q37. What is the right procedure to remove chlorophyll from a destarched leaf ?

1. Boil the destarched leaf in lime water.
2. Boil the destarched leaf in alcohol.
3. Boil the destarched leaf in water only.
4. Boil the destarched leaf in a mixture of alcohol and water.

Q38. When an epidermal of a leaf is observed through a high powered microscope, it shows that each stomata is surrounded by

1. many guard cells.
2. a pair of guard cells.
3. a single guard cell.
4. a pair of epidermal cells.

Q39. An epidermal peel of a leaf was observed by four students A, B, C and D under the high power of a microscope, the following sketches were made by them. Identify the correct sketch

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

Q40. Given below are four different set ups to show that CO2 is released during respiration. The set up that will give the desired result

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

Q3.Why is CNG considered an environmental friendly fuel?

Q4. Name the physical quantity which is same in all the resistors when they are connected in series.

Q10. A student constructed a model of box type solar cooker. Instead of using glass sheet he used a transparent plastic sheet to cover the open face of the box. He found that this cooker does not function well. What could be the possible drawbacks in his model? Explain the advantage of painting black the inner and outer surfaces of the cooker and that of cooking vessels.

Q11. Two students perform experiments on two given resistors R1 and R2 and plot the V - I graphs shown by diagram 1 and 2. If R1> R2, which of the two diagrams correctly represent the situation on the plotted curves? Justify your answer.

Q12. In the figure below, identify the poles marked P and Q as North Pole or South Pole. Give reason for your answer.

Q13. In an electric circuit with a resistance wire and a cell, the current flowing is I. What would happen to this current if the wire is replaced by another thicker wire of same material and same length? Give reason.

Q19. Write three advantages and three limitations of using solar cooker.

Q20. The following circuit diagram shows the combination of three resistors R1, R2 and R3. Find

1. total resistance of the circuit,
2. total current (I) flowing in the circuit and the
3. potential difference across R1.

Q21. Two identical immersion heaters are to be used to heat water, in a large container. Which one of the following arrangement would heat the water faster:

1. connecting the heaters in series with the main supply
2. connecting the heaters in parallel with the main supply

Give reasons for your answer.

Q25.

1. Two circular coils A and B are placed closed to each other. If the current in the coil A is changed, will some current be induced in coil B? Give reason.
2. State the rule to determine the direction of a:
3. magnetic field produced around a straight conductor carrying current.
4. force experienced by a current carrying straight conductor placed in a magnetic field, which is perpendicular to it.

Q31.For the circuit arrangement, shown above the student would observe:

1. some reading in both the ammeter and the voltmeter
2. no reading in either the ammeter or the voltmeter
3. some reading in the ammeter but no reading in the voltmeter
4. some reading in the voltmeter but no reading in ammeter

Q32. The current flowing through a conductor and the potential difference across its two ends are as per readings of the ammeter and the voltmeter shown below. The resistance of the conductor would be:

1. 0.175 Ω
2. 1.75 Ω
3. 17.5 Ω
4. 175 Ω

Q33. Which one of the following plot correctly shows the dependence of the current I on the potential difference V across a resistor R?

Q34. For the circuits A and B shown below, the voltmeter readings would be:

1. 0.6 V in circuit A and 2.5 V in circuit B
2. 0 V in both circuits
3. 1 V in both circuits
4. 0 V in circuit A and 3 V in circuit B

Q35. For determining the equivalent resistance of two resistors R1 and R2 connected in series, three circuits are shown in the figure. The correct circuit is/are:

1. only Q and R.
2. only P and R.
3. All the three.
4. only P and Q.

Q1. Name two components of central nervous system in Humans.

Q4. Write the chemical formula of Bleaching powder. How is bleaching powder prepared? For what purpose is it used in drinking water?

Q5. On heating copper powder in air the surface of copper powder becomes coated with black CuO. How can this black coating be converted into brown copper? Write chemical equation for the reaction that occurs during the colour change.

Q6.

1. Write the balanced chemical equation for the process of photosynthesis.
2. When do the desert plants take-up carbon dioxide and perform photosynthesis?

Q7. Balance the following chemical equations.
Write the symbols of physical states of all the reactants and the products:

Q8. List the raw materials needed for the manufacture of baking soda. Write the balanced chemical equation for this. What happens when baking soda is heated? Write chemical equation.

Q9. You are given samples of three metals – sodium, magnesium and copper. Suggest any two activities to arrange them in order of their decreasing reactivity.

Q10.

1. Mention two observations which you will make on heating ferrous sulphate crystals in a boiling tube.
2. On placing a zinc plate in copper sulphate solution, it was observed that the zinc plate develops holes after a few days. Give chemical equation to explain this.
3. Silver chloride turns grey when exposed to sunlight. Give chemical equation to explain it.

Q11.

1. State two functions of bile juice.
2. Differentiate between the functions of enzymes pepsin and trypsin.

Q12. Give reason to explain why endocrine glands release their secretions into the blood directly.

Q13. Write three points of difference between photosynthesis and respiration.

Q18. List any three advantages of biogas as a source of energy.

Q19.

1. In a tabular form write the colours of the following indicators in presence of acidand base:
   Litmus solution, phenolphthalein solution, methyl orange solution.
2. Classify the following given solutions A and B in acidic and basic, giving reason.
   1. Solution A : [H+ ] < [OH- ]
   2. Solution B : [H+ ] > [OH- ]

Q20. Write the electronic configuration of magnesium (atomic no.12) and oxygen (atomic no.8) and explain the formation of magnesium oxide by electrons transfer. State the type of bond formed. Explain with reason two physical properties of compounds formed by this bonding.

Q21. With the help of a labeled diagram explain the general scheme to illustrate how nervous impulses travel in the body.

Q25. Mix one drop of universal indicator with one drop of given solution and found that a red colour is produced, pH of the solution would be in the range of :

1. 0-3
2. 4-6
3. 6-8
4. 8-10

Q26. Observe the following figures and choose the correct option given below:

1. pH of A, B and C are equal
2. pH of A is greater than pH of B and C
3. pH of C is greater than pH of A and B
4. pH of B is greater than pH of A and C

Q27. A student takes some zinc granules in a test tube and adds dilute hydrochloric acid to it.
He would observe that the colour of the zinc granules changes to:

1. Brown
2. White
3. Yellow
4. Black

Q28. An iron nail was kept immersed in aluminum sulphate solution. Correct observation made after half an hour, would be.

1. The colorless solution changed to green.
2. A grey coating was deposited on iron nail.
3. The iron nail became red, the colorless solution remained colorless.
4. The solution remained colorless and no deposition observed.

Q29. A few pieces of granulated zinc were added to copper sulphate solution in a test tube.
After an hour, the colour of the solution changed from-

1. light green to blue
2. light green to colorless
3. blue to light green
4. blue to colorless

Q1. How many vertical columns are there in the modern periodic table and what are they called?

Q2. What is Speciation?

Q3. Why should biodegradable and Non-biodegradable wastes be discarded in two separate dust bins?

Q4. The chromosomes number of the sexually reproducing parents and their offspring is the same. †Justify this statement.

Q6. We often observe domestic waste decomposing in the bylanes of residential colonies. Suggest ways to make people realize that the improper disposal of waste is harmful to the environment.

Q7. List and explain any two advantages associated with water harvesting at community level.

Q8. Write the name and the structural formula of the compound formed when ethanol is heated at 443 K with excess of cone H2SO4. State the role of cone H2SO4 in this reaction. Write chemical equation for the reaction.

Q9. Why homologous series of carbon compounds are so called? Write chemical formula of two consecutive of a homologous series and state the part of these compounds that determines their

1. physical properties, and
2. chemical properties.

Q10. Given below are some elements of the modern periodic table:
4Be, 9Fe, 14 Si, 19K, 20Ca

1. Select the elements that has one electron in the outermost shell and write its electronic configuration.
2. Select two elements that belong to the same group. Give reason for the answer.
3. Select two elements that belong to the same period. Which one of the two has bigger atomic size?

Q11. Write the number of periods the modern periodic table has. How do the valency and metallic character of elements vary on moving from left to right in a period? How do the valency and atomic size elements vary down a group?

Q12.

1. Explain the process of regeneration in Planaria.
2. How is regeneration different from reproduction?

Q13. Write two examples each of sexually transmitted diseases caused by (i) virus, (ii) bacteria. Explain how the transmission of such diseases prevented?

Q14. Tabulated two distinguishing features between acquired traits and inherited traits with one example of each.

Q15. The sex of a newborn child is a matter of chance and none of the parents may be considered responsible for it. †Justify this statement with the help of flow chart showing determination of sex of a newborn.

Q19.

1. What is an ecosystem? List its two main components.
2. We do not clean ponds or lakes, but an aquarium needs to be cleaned regularly. Explain

Q20.

1. Define the term isomers
2. Draw two possible isomers of the compound with molecular formula C3H5O and write their names
3. Give the electron dot structures ot the above two compounds.

Q21.

1. List three distinguishing features between sexual and asexual types of reproduction.
2. Explain why variations are observed in the offsprings of sexually reproducing organisms?

Q22.

1. Identify A,B and C in the given diagram and write their functions.
2. Mention the role of gamete and zygote in sexually reproducing organisms.

Q25. A student takes 2 mL acetic acid in a dry test tube and adds a pinch of sodium hydrogen carbonate to it. He makes the following observation.

1. A colourless and odourless gas evolves with a brisk effervescence.
2. The gas turns lime water milky when passed through it.
3. The gas burn with an explosion when a burning splinter is brought near it.
4. The gas extinguishes the burning splinter that is brought near it.

Q27. A student prepared 20% sodium hydroxide solution in a beaker containing water. The observations noted by him are given below.

1. Sodium hydroxide is in the form of pellets.
2. It dissolves in water readily.
3. The beaker appears cold when touched from outside.
4. The red litmus paper turns blue when dipped into the solution.

Q28. Read the following statements:

1. When a red litmus paper is dipped into reaction mixture of a saponification reaction, it turns blue and the reaction is exothermic.
2. When a blue litmus paper is dipped into reaction mixture of a saponification reaction, its colour does not change and the reaction is exothermic.
3. When a red litmus paper is dipped into reaction mixture of a saponification reaction, its colour does not change and the reaction is endothermic.
4. When a blue litmus paper is dipped into reaction mixture of a saponification reaction, its colour does not change and the reaction is endothermic.

   Which of the above statements are correct:

1. l, and ll
2. ll and lll
3. lll and lV
4. l and IV>

Q29. Hard water required for an experiment is not available in a school laboratory. However, following salts are available in the laboratory. Select the salts which may be dissolved in water to make it hard for the experiment.

1. 1) Calcium Sulphate
2. Sodium Sulphate
3. Calcium Chloride
4. Potassium Sulphate
5. Sodium Hydrogen Carbonate
6. Magnesium Chloride

Q38. A student after observing a slide showing different stages of binary fission in Amoeba draws the following diagrams. However these diagram are not in proper sequence:

Q39. Select the correct statement for the process of budding in yeast:

1. A bud arises from a particular region on a parent body.
2. A parent cell divides into two daughter cells, here the parental identity is lost.
3. Before detaching from the parent body a bud may from another bud.
4. A bud when detaches from the parent body grows into a new individual.

Q40. Study the different conclusions drawn by students of a class on the basis of observations of preserved/available specimens of plants and animals.

1. Potato and sweet potato are analogous organs in plants.
2. Wings of insects and wings of birds are homologous organs in animals.>
3. Wings of insects and wings of bats are analogous organs in animals.
4. Thorns of citrus and tendrils of cucurbita are analogous organs in plants.

Q41. You have potato, carrot, radish, sweet potato, tomato and ginger bought from the market in your jute bag. Identify two vegetables to represent the correct homologous structures.

1. Potato and tomato
2. Carrot and tomato
3. Potato and sweet potato
4. Carrot and radish

Q42. In the figure, the parts marked A,B and C are sequentially:

1. Plumule, Radicle and Cotyledon
2. Radicle, Plumule and Cotyledon
3. Plumule, Cotyledon and Radicle
4. Radicle, Cotyledon and Plumule

Q2. Give the respective scientific terms used for studying:

1. The mechanism by which variations are created and inherited and
2. The development of new type of organisms from the existing ones.

Q3. Water is a valuable resource. List two ways, that you would suggest every family member to save this resource.

Q4. List four advantages of vegetative propagation.

Q6. Why is Government of India imposing a ban on the use of polythene bags? Suggest two alternatives to these bags and explain how this ban is likely to improve the environment.

Q7. What is meant by biodiversity? List two advantages of Conserving forest and wild life.

Q8. State the meaning of functional group in a carbon compound. Write the functional group present in (i) ethanol and (ii) ethanoic acid and also draw their structures.

Q9. Write the name and general formula of a chain of hydrocarbons in which an addition reaction with hydrogen can take place. Stating the essential conditions required for an addition reaction to occur. Write the chemical equation giving the name of the reactant and the product of such a reaction.

Q10. Based on the group valency of elements state the formula lot the following giving justification for each :

1. Oxides of 1st group elements,
2. Halides of the elements of group 13, and
3. Compounds formed when an element of group 2 combines with, an element of group 16.

Q11.

1. Define the following terms :
2. Valency
3. Atomic size

Q12. Draw diagrams to explain the regeneration that takes place in each of the body parts of planaria when its body is out into pieces. Name any other organisms in which a similar process can be observed.

Q13. List any four methods of contraception used by human. How does their use have a direct effect on the health and prosperity of a family?

Q14.

1. Give the evidence that the birds have evolved from reptiles.
2. Insects, octopus, planaria and vertebrates posses eyes. Can we group these animals together on the basis of eyes that they possess? Justify your answer giving reason.

Q15. A cross was made between pure breeding pea plants one with round and green seeds and the other with wrinkled with yellow seeds.

1. Write the phenotype of F1 progeny. Give reason for your answer.
2. Write the different types of F2 progeny obtained along with their ration when F1 progeny was selfed.

Q19. “Our food grains such as wheat and rice, the vegetables and even meat are found to contain varying amounts of pesticide residues.” State the reason to explain how and why it happens?

Q20. State the reason why carbon an neither form C4+ cations nor C4- anions but forms covalent compounds. Also state the reason to explain why covalent compounds:

1. Are bad conductors of electricity.
2. Have low melting and boiling points.

Q21.

1. Give one example each of a unisexual and a bisexual flower.
2. Mention the changes a flower undergoes after fertilisation.
3. How does the amount of DNA remain constant though each generation is a combination of DNA copies of two individuals?

Q22.

1. Name the respective part of human female reproductive system:
   1. that produces eggs,
   2. where fusion of eggs and sperm takes place, and
   3. where zygote gets implanted.

Q25. When you add about 2 ml of acetic acid to a test tube containing an equal amount of distilled water and leave the test tube to settle after shaking its contents, what will you observe in the test tube after about 5 minutes?

1. A white precipitate settling at its bottom
2. A clear colourless solution
3. A layer of water over the layer of acetic acid
4. A layer of acetic acid over the layer of water.

Q26. A student adds a few drops of ethanoic acid to test tubes X,Y and Z containing aqueous solutions of sodium chloride, sodium hydroxide and sodium carbonate, respectively. If he now brings a burning splinter near the mouth of the test tubes immediately after adding ethanoic acid one of them, in which of the test tube or test tubes the flame will be extinguished?

1. X and Y
2. Y and Z
3. X and Z
4. Only Z

Q27. In order to study saponification reaction, we first prepare 20% solution hydroxide. If we record the temperature of this solution just after adding sodium hydroxide flakes to water and also test its nature using litmus, it may be concluded that the process of making this solution is

1. Exothermic and the solution is alkaline
2. Endothermic and the solution is alkaline
3. Endothermic and the solution is acidic
4. Exothermic and the solution is acidic

Q28. While studying saponification reaction for the preparation of soap, a teacher suggested to a student to add a small quantity of common salt to the reaction mixture. The function of common salt in this reaction is to

1. reduce the alkalinity of the soap
2. reduce the acidity of the soap
3. enhance the cleansing capacity of soap
4. favour precipitation of soap

Q29. A student takes about 6 ml of distilled water in each of the four test tubes P, Q, R and S. He then dissolves an equal amount of four different salts namely. Sodium chloride in ‘P’. Potassium chloride in ‘Q’. Calcium chloride in ‘R’ and magnesium chloride in ‘S’. Next, he then adds 10 drops of soap solution to each test tube and shakes its contents. The test tubes in which scum (insoluble substance) is formed with soap are:

1. P and Q
2. Q and R
3. R and S
4. Q and S

Q38. Study the following diagrams showing various stages of binary fission in Amoeba:
The correct sequence of these diagrams should be:

1. I, IV, III, II, V
2. I, III, IV, II, V
3. I, II, IV, III, V
4. I, II, III, IV, V

Q39. Identify the figures showing the process of budding in yeast.

1. I, II and III
2. II, III and IV
3. I, II and IV
4. III, IV and I

Q40. Which one of the following pairs of vegetables is an example of homologous structures?

1. Potato and sweet potato
2. Carrot and radish
3. Carrot and tomato
4. Tomato and radish

Q41. Four students P, Q, R and S differently reported the following set of organs to be analogous:

1. Forelimb of a frog and forelimb of lizard
2. Forelimb of a bird and forelimb of a human
3. Wings of a parrot and wings of a butterfly
4. Wings of a bird and wings of a bat

The two students who have reported correctly are:

1. P and Q
2. Q and R
3. R and S
4. P and S

Q42. You are asked by your teacher to study the different parts of an embryo of a gram seed. Given below are the step to be followed for the experiment:

1. Soak the gram seeds in plain water and keep them overnight.
2. Cut open a soaked seed and observe its different parts.
3. Take some dry gram seeds in a petri dish.
4. Drain the excess water.
5. Cover the soaked seeds with a wet cotton cloth and leave them for a day.

   The correct sequence of these steps is:

   1. III, I, V, IV, II
   2. III, I, II, IV, V
   3. III, IV, V. I, II
   4. III, I, IV, V, II

Q1. Write the name and formula of the 2nd member of homologous series having general formula CnH2n.

Q2. List two functions performed by the testis in human beings.

Q3. What is the function of ozone in the upper atmosphere?

Q5. Why are forests considered “biodiversity hot spots”? List two ways in which an individual can contribute effectively to the management of forests and wildlife.

Q6. What is meant by “sustainable management”? Why is reuse considered better than recycling?

Q7. With the help of an example, explain the process of hydrogenation. Mention the essential conditions for the reaction and state the change in physical property with the formation of the product.

Q8. What is the difference between the molecules of soaps and detergents, chemically? Explain the cleansing action of soaps.

Q9. How many groups and periods are there in the modern periodic table? How do the atomic size and metallic character of elements vary as we move:

1. Down a group and
2. From left to right in a period

Q10. From the following elements:
4Be; 9F; 19K; 20Ca

1. Select the element having one electron is the outermost shell.
2. Two elements of the same group.

Write the formula of and mention the nature of the compound formed by the union of 19K and element X(2, 8, 7).

Q11. What is DNA copying? State its importance.

Q12. Explain budding in hydra with the help of labelled diagrams only.

Q13. List any four methods of contraception used by humans. How does their use have a direct effect on the health and prosperity of a family.

Q14. “We cannot pass on to our progeny the experiences and qualifications earned during our life time”. Justify the statement giving reason and examples.

Q15.

1. Planaria, insects, octopus and vertebrates all have eyes. Can we group of these animals together to establish a common evolutionary origin? Justify your answer.
2. “Birds have evolved from reptiles” State evidence to prove the statement.

Q18. After the examinations Rakesh with his friends went on a picnic to a nearby park. All friends carried cooked food packed in plastic bags or plastic cans. After eating the food some friends collected the leftover food and plastic bags etc and planned to dispose them off by burning. Rakesh immediately checked them and suggested to segregate the leftover food and peels of fruits from the plastic materials and respectively dispose them off separately in the green and red dustbins placed in the corner of the park.

1. In your opinion, is burning plastic an ecofriendly method of waste disposal? Why? State the advantage of method suggested by Rakesh.
2. How can we contribute in maintaining the parks and roads neat and clean?

Q19. Explain why carbon forms compounds mainly by covalent bon. Explain in brief two main reasons for carbon forming a large number of compounds. Why does carbon from strong bonds with most other elements?

Q20. Write the functions of the following in human female reproductive system: Ovary, oviduct, uterus
How does the embryo get nourishment inside the mother’s body? Explain in brief.

Q21. How many pairs of chromosomes are present in human beings. Out of these, one pair is of sex chromosomes.
“The sex of a newborn child is a matter of chance and none of the parents may be considered responsible for it”. Draw a flow chart showing determination of sex of a newborn to justify this statement.

Q25. A student adds 2 mL of acetic acid to a test tube containing 2 mL of distilled water. He then shakes the test tube well and leaves it to settle for sometime. After about 5 minutes he observes that in the test tube there is:

1. A clear transparent colourless solution
2. A clear transparent pink solution
3. A precipitate settling at the bottom of the test tube
4. A layer of water the layer of acetic acid

Q26. A student prepared 20% sodium hydroxide solution in a beaker to study saponification reaction. Some observations related to this are given below:

1. Sodium hydroxide solution turns red litmus blue
2. Sodium hydroxide readily dissolve in water
3. The beaker containing solution appears cold when touched from outside
4. The blue litmus paper turns red when dipped into the solution

   The correct observations are:

   1. I, II and IV
   2. I, II and III
   3. ONLY III and IV
   4. ONLY I and II

Q27. Hard water is not available for an experiment. Some salts are given below:

1. Sodium chloride
2. Sodium sulphate
3. Calcium chloride
4. Calcium sulphate
5. Potassium chloride
6. Magnesium sulphate

Select from the following group of these salts, each member of which may be dissolved in water to make it hard.

1. I, II, V
2. I, III, V
3. III, IV, VI
4. II, IV, VI

Q28. A student identified the various parts of an embryo of a gram seed and listed them as given below:

1. Testa
2. Plumule
3. Radicle
4. Cotyledon
5. Tegmen

   Out of these the actual parts of the embryo are:

   1. I, II, III
   2. II, III, IV
   3. III, IV, V
   4. II, IV, V

Q29. Four students A, B, C and D reported the following set of organs to be homologous. Who is correct?

1. Wings of a bat and butterfly
2. Wings of a pigeon and a bat
3. Wings of a pigeon and a butterfly
4. Forelimbs of cow, a duck and a lizard

Q34. List two observations which you make when you add a pinch of sodium hydrogen carbonate to acetic acid in a test tube. Write chemical equation for the reaction that occurs.

Q35. Name the type of asexual reproduction in which two individuals are formed from a single parent and the parental identity is lost. Draw the initial and the final stages of this type of reproduction. State the event with which this reproduction starts.