Science - Class X

 Class- X Science 

                                           Time: 3 Hrs   M.M. 80

General Instructions:

a. The Questions paper comprise of five sections: A, B, C, D, E. You are to attempt all the sections.

b. All questions are compulsory.

c. Internal choice is given in section B, C, D & E

d. Question number 1 and 2 in section -A are one mark questions. These are to be answered in about 1 (one) word each.

e. Question numbers 3 to 5 in section-B are two mark questions. These are to be answered in about 30 words each.

f. Question numbers 6 to 15 in Section-C are three marks questions. These are to be answered in about 50 words each.

g. Question numbers 16 to 21 in section-D are five marks questions. These are to be answered in about 70 words each.

h. Question numbers 22 to 27 in section E are bases practical skills. Each question in a two marks question. These are to be answered in brief.

Section-A

Q1. Name a gland in the human which acts as exocrine as well as endocrine. (1)

Q2. Write an aquatic food chain. (1) 

Section-B

Q3. Balance the following chemical equation. (1+1) (a) Fe(s) + H2O(g) Fe3O4(s) + H2(g) (b) FeSO4(s) Heat Fe2O3(s) + SO2(g) + SO3(g)

Q4. Name the energy currency in the living organism when and where is it produced. (2)

Q5. A concave mirror and convex lens are immersed in water. What change do you expect in their focal length? (2) OR Define the term dispersion of white light. State the colour which bends: (1+1) a) The Least b) The Most 

Section-C

Q6. A solution of Potassium chloride when mixed with silver nitrate solution, an insoluble white substance is formed. (1+2) a) Write the chemical equation. b) State the two-type of this reaction. Page 2 of 5

Q7 A small amount of quick lime is added to water in a beaker. (1+1+1) a) Name and define the type of reaction that has taken place.

b) Write balanced chemical equation for the above reaction. Write the chemical name of the product obtained.

c) State two observations that you will make in the reaction. OR Name the acid Present in an ant sting and give its chemical formula. Also give the common method to give relief from it.

Q8 (1+1+1) a) Write the electronic configuration of an element having atomic number 16.

 b) Write valency & valence electron of this element.

c) Position of this element in periodic table.

Q9 Name the following: (½ +½ + ½ +½+½+½)

a) Chamber which receives deoxygenated blood from vena cava.

b) Chamber which pumps oxygenated blood into Aorta. c) Blood vessel which bring oxygenated blood to the heart

d) Chamber which receives oxygenated blood from lungs. e) Organ which store bile

f) Organ which produces bile.

Q10 (1+1+1)

a) Differentiate between sensory and motor neurons.

b) How is brain protected in our body.

c) Name the part of the brain responsible for precision of voluntary actions and maintaining body posture and balance of the body.

Q11. An Object is placed perpendicular to the principal axis of convex lens of focal length 10 cm. The distance of the object from the optical centre of the lens is 15 cm. Calculate the position of image formed and nature of image. (2+½+½)

                                      OR

A convex lens forms a real and inverted image of a needle at a distance of 50cm from it where is the needle placed in front of the convex lens if the image is equal to the size of the object. Also find the power of the lens? (2+1) Page 3 of 5

Q12. A hot plate of an electronic oven connected to a 220V line has two resistance coils A and B each of 24 Ω resistance. Which may be used

(i) Separately

(ii) in Series

(iii) in parallel. What are the currents in three cases? (2+1)

Q13 A wire of length ‘L’ and Resistance ‘R’ is stretched so that the length is doubled and area of cross- section halved. How will (i) Resistance Change and (ii) Resistivity change (1½+1½)

Q14 What is Ozone and How will does it affect any ecosystem. (1+2)

                                     OR

A vegetarian habit is more caloric than non-vegetarian habit. Comment (3)

Q15. Why is biogas plant considered to be boon for farmers? Give reasons. (1+2) 

Section-D

Q16. Two ores A and B were taken. On heating, Ore A gives CO2 whereas Ore B give SO2. What steps will you take to convert them into metals? (5)

Q17. Identify the Compound (A to E) in the following reactions. (1+1+1+1+1) a) CH3CH2OH Alkaline KMnO4 A + H2O heat b) CH3CH2OH Con.H2SO4 B + H2O 443 K c) C+ NaOH CH3COONa + CH3OH d) D+ NaHCO3 CH3COONa + H2O + E OR Explain Isomers. Write any four characteristics. Write the three Isomers of C5H10 and also write their IUPAC name. (1+1+½+½+½+½+½+½)

Q18. (3+2) a) Describe double fertilisation in plants? b) Why is the number of sperms produced in males always more than the number of ova produced in females? Page 4 of 5

Q19. A blue colour flower plant denoted by BB in cross-breed with a white colour flower plant denoted by WW. (2+2+1) a) State the colour of flowers use you would expect in their F1 progeny. b) Write the percentage of plants bearing white flower in F2 generation when the flowers of F1 plants were selfed. c) State the expected ratio of genotype BB and BW in the F2 generation.

                               OR

What is tidal energy? How can we utilise tidal energy? Write its merits and demerits? (1+2+2)

Q20. What is Presbyopia? What causes presbyopia? How is it corrected? (5)

Q21. (2+3)

a) What is a magnetic field? How can the direction of magnetic field lines at a place be determined?

b) State the rule for the direction of Magnetic field produced around a current- carring straight conductor. Draw a sketch of pattern of field lines due to a current flowing through a straight conductor.

                            OR

Name a device which converts electrical energy into Mechanical energy. Explain its principle and working of this device with the help of labelled diagram. (5) Section –E

Q22. In an experiment a student found that on heating Zinc metal with dilute sodium hydroxide solution a gas is evolved. Which properties are shown by the evolved gas and give equation. (1+1)

Q23. A student was asked to use convex lens and he obtained a sharp image of distant object on screen. In order to determine the focal length of a lens, what should he do? (2)

Q24. You are provided with small pieces of silver and iron. Which pieces, do you think, would change the blue solution of copper sulphate in a test tube? (2)

Q25. For demonstrating the release of CO2 during respiration teacher used lime water instead of plain water. What observations are likely to be made? (2) OR While testing the presence of starch which leaf would you prefer – normal or variegated? Justify your answer. (2) Page 5 of 5

Q26. In order to study the different parts of an embryo of a dicot seeds, a teacher provides seeds of kidney bean, maize and gram. (1+1) a) Which seeds will you choose for this experiment? b) On What basis do you choose the specific seeds?

Q27. In an experiment a student connected a cell in series with an ammeter and three resistors (10 Ω, 20 Ω, 30 Ω). The circuit can be completed by a movable contact M. When he connected M with X. The ammeter read 0.6 A. What is the ammeter reading when M is connected to Y.? (2) 

                              OR

 In an experimental setup for determination of resistance of a given resistor, it is advised to take out the plug from the key when the observations are not being taken. Why?