Preboard Exam 2017-18
Class-X
Time : 3 hours.Subject: ScienceM.M: 80
General instructions
(i)The question paper comprises two sections A and B. you are to attempt both the sections.
(ii)All questions are compulsory.
(iii)All questions of section A and B are to be attempted separated.
(iv)There is an internal choice in three questions of three marks each and two questions of five marks.
(v)Question numbers 1 and 2 in section are 1 mark question. They are to be answered in one word or in one sentence.
(vi)Question numbers 3 to 5 in section-A are 2 marks questions. These are to be answered in 30 marks each,
(vii)Question numbers 6 to 15 in section –A are 3 marks questions. These are to be answered in about 50 words each.
(viii)Question numbers 16 to 21 in section –A are 5 marks questions. These are to be answered in 70 words each.
(ix)Question numbers 22 to 27 in section-B are based on practical skills. Each question is a two marks question. These are to be answered in brief.
Section-A
1. / N2+3H2→2NH3 .Name the type of reaction / 12. / An atom has electronic configuration 2,8,7. What is the atomic number of this element? / 1
3. / How is the process of pollination different from fertilization? / 2
4. / Write two uses of concave mirror. / 2
5. / Biogas is considered to be a boon to the farmers. Give reason. / 2
6. / Give reasons for following
(a)Aluminium is a reactive metal but it is still used for packing food articles. / 1+ ½
(b)Calcium starts floating when water is added to it. / 1+ ½
7. / What is hydrogenation? What is its industrial application? / 2+1
8. / The elements calcium, strontium and barium have been put together in same group on basis of similar properties.
(1)What are those similar properties? / 2
(2)What is the common name of this group? / 1
9. / (a) How does the transport of materials in xylem and phloem occur? / 2
(b) What is translocation? / 1
10. / Define reflex action. Give one example. Show with the help of flow diagram of path followed in relex action. / ½ + ½ + 2 = 3
11. / What are sexually transmitted diseases? Name three diseases. Which one of them damage the immune system of body? / 3
OR
Name the following parts :-
(a)A funnel like structure near the posterior end of ovary / 1
(b)Birth canal / 1
(c)The organ where foetus develops during pregnancy / 1
12. / Differentiate between inherited and acquired traits. Give one example of each type. / 2+1=3
OR
What are fossils? What do they tell us about the process of evolution? / 1+2=3
13. / A torch bulb is rated 5V and 500mA. Calculate its (a) power (b) resistance (c) energy consumed when it is lighted for 4 hours. / 1+1+1=3
14. / List three factors which can cause overloading of domestic electric circuits.
OR / 3
Explain whether an alpha particle will experience any force in a magnetic field if:-
(a)It is placed in the field at rest.
(b)It moves in the magnetic field parallel to the field lines
(c)It moves in the magnetic field perpendicular to field lines. / 1+1+1=3
15. / A concave lens of focal length 15cm forms an image 10cm from the lens. How far is object placed from lens. Draw ray diagram. / 2+1=3
16 / (a)What is the chemical name and chemical formula of plaster of paris?
(b)Write a reaction between plaster of paris and water.
(c )Write two uses of washing soda.
(d)What is chlor –alkaiprocess? Name two products obtained during this process. / 1/2+1/2=1
1
1
1+1/2+1/2=2
17. / (a)State any three physical properties of carbon compounds.
(b)Carbon is versatile element. Give two reasons. / 3
2
OR
(a)Why are covalent compound generally poor conductor of electricity?
(b)Name the following compound:-
CH3-CO-CH3
(c )Name the gas evolved when ethanoic acid is added to sodium carbonate. How will you prove the presence of this gas? / 2
1
1+1=2
18. / Explain with the help of diagram, Mendel’s monohybrid cross.
OR
What is speciation? What are the factors that leads to speciation? Explain any two factors. / 5
1+2+2=5
19. / What are magnetic field lines? List three characteristics of these lines. Describe in brief an activity to study the magnetic field lines due to a current flowing in a circular coil. / 1+3+1=5
20. / (a)What is hypermetropia?
(b)What are the two causes of this defect of vision?
(c )How can this defect of the eye be corrected? / 1
2
2
21. / (a)What are food chains? Give one example.
(b)List characteristics of food chain.
(c )What will happen if deer are killed in the following chain:-
grass→Deer→Lion / 2
2
1
Section-B
22 / A student observed a permanent slide showing asexual reproduction in yeast. Draw diagram of the observation he must have made from slide.Name the process also. / 2
23. / Write two properties of an acid based on taste and reaction with metals. / 2
OR
Write two properties of a base based on taste and reaction with metals. / 2
24. / In an experiment to prepare the temporary mount of a leaf peel to show stomata, why glycerin and safranin are used? / 1+1=2
25. / In a voltmeter there are 20 divisions between the 0V mark and 0.5V mark. Calculate the least count of the voltmeter. / 2
26. / What happens when Barium chloride solution and sodium sulphate are mixed together. Write the chemical reaction. / 2
27. / Explain how we connect an ammeter and a voltmeter in a circuit while performing experiment. / 2
*******************End of Paper***************************
Marking scheme
Class –X
Subject-science
1. / Combination reaction / 12. / 17 / 1
3 / Pollination :- Transfer of pollen grains / 1
Fertilization :- fusion of male and female gamets / 1
4. / Uses i) In hospitals / 1
ii) In makeup mirror / 1
5. / i) production of clean fuel / 1
ii) Slurry used as manure / 1
6. / There is shining coating of aluminum oxide on foil bubbles of H2 gas formed on surface of metal / 1
1
7. / Adding of Hydrogen to on saturated Hydrocarbon and application / 1+1=2
8. / a) Any two properties / 2
b) alkaline earth metals / 1
9. / a) xylem :- Transport of water / 1
Phloem : Transport of food / 1
b) Transport of soluble food by phloem / 1
10. / Definition of reflex action / 1
E.g.: pulling out hand from flame / 1
Diagram of reflex arc / 1
11. / Definition of sexually transmitted disease / 1
e.g. : Gonorrhea, syphilis, AIDS / 1+1/2
AIDS damage immune system / 1/2
OR
a) Fallopian tube / 1
b) Vagina / 1
c) Uterus / 1
12. / Inherited :- transfer from one generation to next / 1 ½
e.g. : eye colour
Acquired :- Picked up after birth
e.g. : Body weight / 1 ½
OR
Fossils : Dead remains of living organisms. It helps in support of organic evolution and determining evolutionary relationship / 1+2=3
13 / i) P = VI = 5×0.5 = 2.5 watt / 1
ii) R= = = 10 Ω / 1
iii) W = p×t= 2.5×4= 10J / 1
14. / Any three factors / 3
OR
i) No, because charged particle at rest. / 1
ii) No, because force is zero, if current and magnetic field are in same direction / 1
iii) Yes, force is maximum / 1
15. / =
U=-30cm / 2
Correct ray diagram / 1
16 / a) chemical name : plaster of Paris / 1/2
Chemical formula:-CaSO4. H2O / 1/2
b) CaSO4. H2O + H2O → CaSO4. 2H2O / 1
c) Any two uses / 2
d) Electrolysis of aqueous of sodium chloride equation / 1
17 / a) Any three properties / 3
b) Two reasons / 2
OR
a) Because there is no free electron / 1
b) Propanone / 1
c) Carbon dioxide / 1
d) It becomes milky when passes through lime water / 2
18. / Correct explanation of monohybrid cross with diagram / 5
OR
Speciation :- formation of new species from existing species / 1
Factors :i) Natural selection / ½ * 4 =2
ii) Genetic drift
iii) Geographical Isolation
iv) Reproductive Isolation
Explanation of any two factors / 2
19. / Definition of magnetic fine / 1
Three characteristics / 3
Description of an activity / 1
20 / Definition of hypermetropia / 1
Any two causes / 2
Correction of this defect / 2
21. / Definition & e.g. of food chain / 1+1=2
Characteristics of food chain / 2
Food chain will be disturbed / 1
22. / Correct diagram / 1
Budding / 1
23. / Any 2 properties of acid / 2
OR
Any two properties of bases / 2
24. / Glycerin :- Avoids the drying of specimen / 1
Saffaranin :- for highlight the cell organizes
25. / Least count :- =0.025
26. / Barium sulphate is formed / 1
BaC12+Na2SO4 →BaSO4+2NaC1 / 1
27. / In series / 1
In parallel / 1