Q2. What is a universal indicator? …

Q2. What is a universal indicator? Q3. The radius of curvature of a spherical mirror is 20 cm. What is its focal length? Q4. What will happen if platelets were absent in the blood? Q5. What will happen to a plant if its xylem is removed? OR Which is the largest gland in the human body? Q6. Define photolysis. Q7. State the laws of reflection. OR Define the term principal axis of a spherical mirror. Q8. What is meant by the power of a lens? Q9. Why does the sky appear dark to astronauts? ` Q10. Define one volt. OR Define the term electrical resistivity of a material. Q11. Name the type of blood vessels, which carry blood from organs to the heart. Q12. What happens if a current-carrying conductor is placed in the magnetic field? Q13. Why are crop fields known as artificial ecosystems? OR List two biotic components of a biosphere. For question numbers 14, 15 and 16, two statements are given-one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below: (a) Both A and R are true and R is the correct explanation of the assertion. (b) Both A and R are true but R is not the correct explanation of the assertion. (c) A is true but R is false. (d) A is false but R is true. Q14. Assertion: When HCl is added to zinc granules, a chemical reaction occurs. Reason: Evolution of gas and change in colour indicates that the chemical reaction is taking place. Q15. Assertion: The *** of a child is determined by the mother. Reason: Humans have two types of *** chromosomes XX and XY. Q16. Assertion: Decomposers act as cleaning agents of the environment. Reason: The decomposers recycle waste material in the hydrosphere. OR Assertion: Green plants of the ecosystem are the producers. Reason: Producers trap the radiant energy of the Sun and change it into chemical energy. Q17. Read the following and answer any four questions from 17.1 to 17.5. In human beings, the air is taken into the body through the nostrils. From here, the air passes through the throat and into the lungs. Rings of cartilage are present in the throat. 17.1 Which of the following prevent collapsing of the trachea? (a) Diaphragm (b) Alveoli (c) Rings of cartilage (d) Ribs 17.2 Which is the correct sequence of air passage during inhalation? (a) Nostrils " larynx " pharynx " trachea " lungs (b) Nasal passage " trachea " pharynx " larynx " alveoli (c) Larynx " nostrils " pharynx " lungs (d) Nostrils " pharynx " larynx " trachea " alveoli 17.3 During respiration exchange of gases take place in: (a) trachea and larynx (b) alveoli of lungs (c) alveoli and throat (d) throat and larynx 17.4 Which of the following statement(s) is are true about respiration? I. During inhalation, ribs move inward and the diaphragm is raised. II. In the alveoli, the exchange of gases takes place i.e., oxygen from alveolar air diffuses into blood and carbon dioxide from the blood into the alveolar air. III. Haemoglobin has a greater affinity for carbon dioxide than oxygen. IV. Alveoli increase surface area for the exchange of gases. a) I and IV (b) II and III c) I and III (d) II and IV 17.5 When air is blown from the mouth into a test tube containing limewater, the limewater turned milky due to the presence of: (a) oxygen (b) carbon dioxide (c) nitrogen (d) water vapour Q18. In the Modern Periodic Table, metals are towards the left-hand side, non-metals are towards the right-hand side and there is a zig-zag line between them that contains metalloids. Metals are electropositive, i.e., they have a tendency to lose electrons. As the effective nuclear charge acting on the valence shell electrons increases across a period, the tendency to lose electron will decrease so the metallic character decreases. Down the group, the effective nuclear charge experienced by valence electrons is decreasing because the outermost electrons are farther away from the nucleus. Therefore, they can be lost easily and thus metallic character increases down the group. Non-metals on the other hand, are electronegative. They tend to form bonds by gaining electrons. Non-metallic character increases along the period and decreases down the group. 18.1 Which of the following element is not a metalloid? (a) Ge (b) As (c) Ar (d) Te 18.2 The order of metallic character of some elements is N < P < As < Sb < Bi. The most electronegative among these elements is (a) N (b) P (c) Sb (d) Bi 18.3 Which of the following statements is correct? (a) Electro negativity increases down the group. (b) Metallic character decreases down the group. (c) Effective nuclear charge decreases down the group. (d) The force of attraction between the nucleus and the outermost electrons increases down the group. 18.4 Which of the following property increases along the period? (a) Atomic size (b) Metallic character (c) Electro positivity (d) Non-metallic character 18.5 Which of the following is the most non-metallic element? (a) P (b) Cl (c) Se (d) Br 19.Read the following and answer any four questions from 19.1 to 19.5. The magnetic field lines around a straight conductor (straight wire) carrying current are concentric circles whose centres lie on the wire. It has been shown by experiments that the magnitude of the magnetic field produced by a straight current-carrying wire at a given point is: (i) directly proportional to the current passing in the wire, and (ii) inversely proportional to the distance of that point from the wire. The magnetic field lines are circular near the current-carrying a circular loop. As we move away, the concentric circles representing magnetic field lines become bigger and bigger and at the centre the magnetic field lines are straight. 19.1 The direction of the magnetic field developed around a current-carrying conductor can be easily found by the use of: (a) Fleming’s left-hand rule (b) Left-hand thumb rule (c) Right-hand thumb rule (d) Fleming’s right-hand rule 19.2 A technique of taking an image of different body organs which is based on the magnetic effect of current is (a) MRI (b) X-ray (c) sonography (d) None of these 19.3 The strength of magnetic field due to a straight conductor depends on the: (a) nature of conductor (b) current passing through the wire (c) direction of current (d) all of above 19.4 Which of the following correctly describes the magnetic field near a long straight wire? (a) The field consists of straight lines perpendicular to the wire (b) The field consists of straight lines parallel to the wire (c) The field consists of radial Lines originating from the wire (d) The field consists of concentric circles centred on the wire 19.5 The strength of magnetic field inside a long current carrying straight solenoid is: (a) same at all points (b) minimum in the middle (c) found to increase from one end to the other (d) more at the ends than at the centre. 20. Read the following and answer any four questions from 20.1 to 20.5 A student took HC1 in a conical flask and was placed on a white tile with a cross mark. When seen through the flask the mark was visible. On adding some sodium thiosulphate in the flask the cross marked disappeared when seen through the flask. The student observed some reaction as Sample Paper Class 10 Science Set 1.6 (i) Name the type of reaction seen in the setup. (a) Redox reaction (b) Precipitation reaction (c) Displacement reaction (d) Double displacement reaction (ii) Why did the cross mark disappear? (a) The insoluble precipitate that is formed in the flask does not allow the light to pass through it to see the cross mark. (b) The resultant solution is dark coloured which does not allow the light to pass through it. (c) The resultant solution has high viscosity due to which it refracts the light to other angle. (d) The solution so formed has ability to absorb black colour hence black coloured cross is not seen. (iii) Give the chemical formula of the gas formed in the reaction. (a) SO2 (b) SO3 (c) O2 (d) Cl2 (iv) Name the resultant insoluble substance formed in the flask. (a) Sodium sulphide (b) Sodium sulphate (c) Sodium sulphite (d) Sulphur (v) Which of the following reaction is of similar type as observed in the given set up. Sample Paper Class 10 Science Set 1.16 SECTION B Q21. Name a metal for each case: (i) It does not react with cold as well as hot water but reacts with steam. (ii) It does not react with any physical state of water. Q22. (i) What happens when an acid reacts with a metal carbonate? Give chemical equation involved. (ii) Which gas is usually liberated when an acid reacts with a metal. OR A milkman adds a very small amount of baking soda to fresh milk. (i) Why does he shift the pH of the fresh milk from 6 to slightly alkaline? (ii) Why does this milk take a long time to set as curd? Q23. What processes would you consider essential for maintaining life? Q24. What is the role of the acid in our stomach? OR List two ways in which plants can get rid of the wastes. Q 25. State the cause of dispersion when white light enters a glass prism. Explain with a diagram. Q26. An electric oven of 2 kW power rating is operated in a domestic electrical circuit of 220 V that has a current rating of 5 A. What result do you expect? Explain. SECTION-C Q27. (i) Write two observations when lead nitrate is heated in a test tube. (ii) Name the type of reaction. (iii) Write a balanced chemical equation to represent the above reaction. Q28. Suggest three contraceptive methods to control the size of human population which is essential for the health and prosperity of a country. State the basic principle involved in each. Q29. Why does the sun appear reddish early in the morning? Will this phenomenon be observed by an observer on the moon? Justify your answer with a reason. 30.(A) Which of the following reactions is/ are an endothermic reaction(s) where decomposition also happens? i) Respiration ii)Heating of lead nitrate iii) Decomposition of organic matter iv) Electrolysis of acidified water (B) Silver chloride when kept in the open turns grey. Illustrate this with a balanced chemical equation. Q31. In a pea plant, the trait of flowers bearing purple colour (PP) is dominant over white colour (pp). Explain the inheritance pattern of F1 and F2 generations with the help of a cross following the rules of inheritance of traits. State the visible characters of F1 and F2 progenies. OR What is the variation? How is a variation created in a population? How does the creation of variation in a species promote survival? Q32. State the laws of refraction of light. Explain the term ‘absolute refractive index of a medium’ and write an expression to relate it with the speed of light in a vacuum. Q33. Why should there be equitable distribution of resources? List three forces that would be working against an equitable distribution of our resources. SECTION-D Q34. (i) A copper coin is kept immersed in a solution of silver nitrate for some time. What will happen to the coin and the colour of the solution? (ii) Write the equation involved. (iii) Show the formation of Na2O and MgO by transfer of electrons. Name the ions present in these compounds. OR For making a cake, baking powder is taken. If at home your mother uses baking soda instead of baking powder in cake. (i) How will it affect the taste of the cake and why? (ii) How can baking soda be converted into baking powder? (iii) What is the role of tartaric acid added to baking soda? Q35.How the process of fertilization takes place in plants? Draw labelled diagram to explain the process. OR (a) Explain the role of the placenta in the development of the human embryo. (b) Give an example of two bacterial and two viral sexually transmitted diseases. Name the most effective contraceptive which prevents the spread of such diseases. Q36. i. Define a real image of an object. ii. Name the mirror that (a) can give real as well as a virtual image of an object. (b) will always give a virtual image of the same size as an object. (c) will always give the virtual and diminished image of an object. (d) is used by a doctor in examining teeth. iii. With the help of a ray diagram explain the use of concave mirror as solar concentrators.

What is the function of petal and sepal.

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