II F1315S-PP1-State X Std Soln 1

State - Practice Paper I for Class X Science

II F SnT 2013-15 Date: January, 2015

Time : 3 Hours Max. Marks : 80

Solution to Pracitce paper I I. Four alternatives are provided for each question. Choose the most appropriate

alternative and write it in the space provided. 10 1 = 10

1. Localised form of obtaining electrical energy can be done by using (A) Nuclear power reacher (B) Thermal power station (C) Solar cell panels (D) Hydroelectric power Ans (C)

2. The ultrasound wave send by a transmitter of a sonar returns in 6s from the floor of the ocean to the receiver, the sonar is at a ___________ distance from the floor (A) 3 km (B) 6 km (C) 4.5 km (D) 9 km Ans (D)

3. Which of the following is used to remove acidic stain on clothes? (A) Sodium palmitate (B) Sodium oleate (C) Sodium dodecylsulphate (D) Sodium stearate Ans (C)

4. In nuclear power plant the scarcity of boron rods results in (A) bursting of reactor (B) nuclear reaction is completely stopped (C) melting of core (D) electricity generation decreases Ans (A)

5. When a small piece of sodium is dropped into water, the liberated gas which may catch fire is (A) hydrogen (B) oxygen (C) helium (D) nitrogen Ans (A)

6. The hydrocarbons derived out of fats are (A) aromatic hydrocarbons (B) aliphatic hydrocarbons (C) proteins (D) carbohydrates Ans (B)

7. The chief salt that causes hardness of water is (A) sodium chloride (B) potassium chloride (C) copper sulphate (D) calcium chloride Ans (D)

II F1315S-PP1-State X Std Soln 2

8. Raghu is suffering from very high temperature and viral infection. Which part of his brain is not functioning properly? (A) Cerebrum. (B) Hypothalamus. (C) Cerebellum. (D) Pons. Ans (B)

9. The decomposition of which part of an animals body adds phosphorous to nature? (A) Hair (B) Bones (C) Muscles (D) Blood. Ans (B)

10. Concentrated nitric acid is added to a sample of cooking oil to detect adulteration, If an adulterant is present, it turns (A) yellow in colour. (B) black in colour. (C) reddish brown in colour. (D) yellowish brown in colour. Ans (C)

II. Match the terms in column A with the related explanation in column B. 4 1 = 4 11.

Column A Column B 1] Prolactin a] controls metabolic rate 2] Calcitonin b] regulates uterine contraction 3] Thyroxine c] controls milk production 4] Oxytocin d] decreases the amount of calcium in blood

Solution 1-c, 2-d, 3-a, 4-b

III. Answer the following questions: 7 1 = 7

12. Name the efficient fuel from cow dung? Also mention its main constituents. Solution Biogas methane and Hydrogen.

13. What should be the mass of a star in the stage of red giant to turn into white dwarf? Solution Less than 1.4 times the mass of the sun.

14. A star is said to have yellowish white colour what could be its surface temperature? Solution 6,000 K to 10,000 K

15. What is transmutation? Give an example. Solution The changing of one element into another is called transmutation.

42

22286

22688 HeRnRa

16. Write the electronic configuration of iron atom. Solution The electronic configuration of iron is 1s22s22p63s23p64s23d6

II F1315S-PP1-State X Std Soln 3

17. Name the products of incomplete combustion of automobile fuels. Solution Carbon soot and carbonmonoxide

18. What is the structural formula of n-butane Solution The structural formula of n-butane is CH3CH2CH2CH3

IV. Answer the following questions 16 2 = 32

19. Write any two applications of simple harmonic motion Solution (a) SHM of a pendulum was used for the measurement of time (b) Tuning of musical instrument is done with the vibrating tuning fork which executes SHM

20. (a) No engine is 100% efficient why? (b) A person develops an engine whose efficiency is 45% what do you mean by this? Solution (a) Even a best designed engine can convert only a part of heat supplied into work. Thus the efficiency is not 100% (b) If an engine converts only 45% of the fuel consumed into work, then its efficiency is 45%.

21. A sound wave has a velocity of 450 ms1 calculate the frequency of the wave, if the wavelength of the wave is 90 cm Solution Given v = 450 ms1, = 90 cm = 0.9 m

v 450 450 10v f f 500 Hz0.9 1 9

22. What happens to a red giant with mass more than 1.4 times the mass of sun Solution The star would undergo supernova explosion to become a neutron star or black hole if the mass is very much higher than the sun (about 30 times)

23. An engine is designed to convert 20% of heat energy into work. If the steam in the engine has 80 kJ of heat energy what is the useful work done by the engine? Solution

W 100H

3

3

20% H 20 80 10WH 80 10 J 100 100

W = 16 kJ

24. Name the nuclear radiation which cause highest frequency. What damage do they cause to our body? Solution The nuclear radiation with highest frequency is rays. Its worst possible damage to the human kind in the genetic manipulation resulting in defective offspring.

II F1315S-PP1-State X Std Soln 4

25. How is amorphous silicon obtained? Solution Finely powdered silica, is mixed with magnesium powder and heated in a fine clay crucible. MgO and Si are obtained. The product is washed with dilute HCl to dissolve MgO. Then again it is washed with HF to remove unchanged silica. The powder left behind is amorphous silica.

MgO2SiMg2SiO2

26. Write the molecular and structural formula of benzene. Solution Molecular formula is C6H6 Structural formula is

27. Give two reasons why hard water is not fit for industrial boilers. Solution (a) It forms scales and may result in bursting. (b) It consumes more fuel which is not economical.

28. Distinguish between (a) gaseous cycle and sedimentary cycle (b) myxoderma and cretinism. Solution

Gaseous cycle Sedimentary cycle (i) Reservoir part is the atmosphere or the

hydrosphere Reservoir part is the lithosphere of the earth

(ii) Involves gaseous elements such as O2, CO2 Involve solid elements such as sulphur, calcium, phosphorus

(iii) Perfect cycles Imperfect cycles (iv) Elements move more or less uniformly Elements get locked in the reservoir pool and go out

of circulation for long periods (v) Relatively fast cycles Cycles are quite slow

Myxedema Cretinism Adult hypothyroidism Neonatal hypothyroidism Body temperature drops with that the environment.

Body temperature will be constant and does not alter with the environment.

29.

(a) (b) (i) Identify the above muscles. (ii) Where do you find them?

II F1315S-PP1-State X Std Soln 5

Solution (i) (a) Striped muscles; (b) Cardiac muscles. (ii) (a) Striped muscles are usually attached to the bones. Hence, also called skeletal muscles.

These are elongated and unbranched. (b) Heart is made up of cardiac muscles. These muscle fibres are striated and branched.

30. Give reasons. (a) People living in coastal areas do not suffer from goitre. (b) Adrenaline is called emergency hormone. Solution (a) People living in coastal areas do not suffer from goiter.

Goiter is caused by the hyposecretion of thyroxine due to iodine deficiency. The soil and water in the coastal area has sufficient iodine and hence people there do not suffer from iodine deficiency and hence goiter.

(b) Adrenaline regulates the heartbeat, controls blood pressure and prepares the body to face the emergency situations like emotional disturbances (anger, excitement etc.)

31. Using special enzymes, scientists have successfully isolated the gene that controls the production of insulin and have inserted this gene into the DNA of certain bacteria. These bacteria can now produce insulin. What is this technique known as? Define. Solution Genetic engineering. The process of effecting desirable changes in the genetic material of an organism is called genetic engineering, more precisely the recombinant DNA technology.

32. (a) Deforestation destroys the environment. Explain. (b) Ganesh is a honey vendor. He wanted to make profit. What would he choose to do and how? Solution (a) Deforestation results in decrease in the number of plants which disturbs the O2 -CO2 balance, affects the water cycle and disturbs the food chain.

(b) Ganesh can adulterate the honey with jaggery and sugar.

33. Write any two characteristics of Pteridophytes. Solution Pteridophytes are the primitive vascular plants. The main plant body is sporophyte (2n). Sporophyte reproduces by spores formed in sporangia. The gametophytic plant body (n) is prothallus. It shows clear alternation of generations. The sporophyte and gametophyte are independent of each

other.

34. (i) A farmer observes that his land has plenty of insectivorous plants and decides not to cultivate immediately there and to wait for a season or two. Why?

(ii) Name the process that results in sudden heritable changes in an organism. Solution (i) Insectivorous plants grow more in nitrogen deficient land, where no proper growth of plants can

happen. Hence, the farmer decided to postpone cultivation. Here the insectivorous plants serve as nitrogen level indicators in the soil.

(ii) Mutation.

II F1315S-PP1-State X Std Soln 6

CH2OH

CHOH

CH2OH

V. Answer the following questions 5 3 = 15

35. Explain how doping in p-type semiconductors increases the conductivity? Solution When a trivalent impurity atom, say indium (or boron or gallium (or) aluminium) having three valence electrons is added to pure germanium (or) silicon crystal we get extrinsic semiconductor known as p-type semiconductor It forms three covalent bonds with the neighbouring atoms and fourth bond remains incomplete which has a deficiency of one electron This deficiency acts as a hole which attracts electrons from the neighbouring covalent bond to fill itself These moving holes act as current carries and contributes to increase of conductivity.

36. Show with an example that iron is capable of displacing less reactive metals from the solution of their salts. Solution Iron nail is suspended in copper sulphate solution. When an iron nail is suspended in a beaker containing copper sulphate solution with the help of thread. After sometime we observe that iron displaces copper from copper sulphate solution to form iron sulphate.

CuFeSOCuSOFe 44

37. What is LPG? Name the main component of LPG? Why is it a popular fuel? Solution LPG is a domestic hydrocarbon fuel. The main component of LPG is butane. It is a popular fuel because it is eco-friendly, it has high calorific value, it can easily be compressed and stored.

38. (a) Mention the carbon compound having 3 on functional group and write structure formula of it. (b) Describe than tetra valency of carbon Solution (a) The carbon compound having three OH functional groups is glycerol or propane 1, 2, 3 trial. The structural formula of glycerol is (b) A carbon atom has four valence electrons so, it needs four more electrons to complete its octet. A carbon atom completes its octet by sharing its valence electrons with other atoms. As a result, carbon atoms forms four covalent bonds by sharing valence electrons with other atoms. Thus is known as tetra valency of carbon.

39. Renu touches a hot pot accidentally while cooking and she removes her hand immediately. (a) Which part of the nervous system is involved in this action? (b) What is this action called? (c) What do hot pot and removal of hand represent in this action?

Si Si Si

Si B Si

Si Si Si

Hole

II F1315S-PP1-State X Std Soln 7

Solution (a) Spinal cord. (b) Reflex action. (c) Hot pot: Stimulus Removal of hand: Response

VI. Answer the following questions 3 4 = 12

40. With a neat diagram explain the working of an induction coil. Solution An induction coil is a device for obtaining a very high DC voltage starting from a low DC voltage An induction coil consists of

(a) few turns of a primary coil P of thick insulated copper wire wound over a soft iron core connected to a battery.

(b) S is a secondary coil of large number of turns wound over the primary coil (c) M is a make and break arrangement

When the DC current flows in the primary, C gets magnetized. The iron head H of the switch M is attracted towards C so, the circuit breaks and the current in primary stops. C gets demagnetized and H comes back the process repeats.

During make and break of the circuit, large emf is induced in the secondary. The voltage depends on the turns ratio. Since the number of turns in secondary is very large, a large

voltage is produced in the secondary coil.

41. Draw a neat diagram of the electrolyte cell to show refining of copper. Name the electrolyte and electrodes used. Solution Electrolyte copper sulphate solution Electrodes Anode blister copper cathode

pure copper plates

S

T1 T2

H M

B K

C

P INDUCTION COIL

Cathode

Anode

+

Copper sulphate solution

Anode Cathode

Electrolytic cell for purification of copper

II F1315S-PP1-State X Std Soln 8

42. (a) Draw the L.S of a flower and label the reproductive parts. (b) How are monocot flowers different from dicot flowers? (c) List any two characteristic features of chordates. Solution (a) L.S. of a flower. The reproductive parts of the flower are stamen and pistil.

(b) Monocot flowers are trimerous whereas, flowers of dicots are tetramerous or pentamerous. (c) Chordates exhibit the following characteristic features:

(i) Presence of a solid supporting structure on the dorsal side of the body called notochord. (ii) Presence of a dorsal, tubular nerve cord. (iii) Presence of openings in the pharynx called gill slits, atleast in the embryonic stages.

* * *

Petals

Sepal

Stigma

Style Ovary

Pistil Anther Stamen