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Board Paper of Class 10 2017 Science (SET 2) - Solutions

(i) The questions paper comprises two section, A and B. You are to attempt both the sections.
(ii) All questions are compulsory.
(iii) There is no choice in any of the questions.
(iv) All questions of Section A and all questions of Section B are to be attempted separately.
(v) Question numbers 1 to 3 in Section A are one mark questions. These are to be answered in one word or one sentence.
(vi) Question numbers 4 to 6 Section A are two marks questions. These are to be answered in about 30 words each.
(vii) Question numbers 7 to 18 in Section A are three marks questions. There are to be answered in about 50 words each.
(viii) Question numbers 19 to 24 in Section A are five marks questions. These are to be answered in about 70 words each.
(ix) Question number 25 to 33 in Section B are multiple choice questions based on practical skills. Each question is a one mark question. You are to select one most appropriate response out of the four provided to you.
(x) Question numbers 34 to 36 in Section B are two marks questions based on practical skills. These are to be answered in brief.

  • Question 1
    Write the molecular formula of first two members of homologous series having functional group −Br.    VIEW SOLUTION

  • Question 2
    How does Planaria reproduce? Is this method sexual or asexual?   (1) VIEW SOLUTION

  • Question 3
    Why is forest considered a natural ecosystem?  VIEW SOLUTION

  • Question 4
    An object is placed at a distance of 40 cm in front of a convex mirror of radius of curvature 40 cm. List four characteristics of the image formed by the mirror.  VIEW SOLUTION

  • Question 5
    Why is sustainable management of natural resources necessary? Why is reuse better as compared to recycle?  VIEW SOLUTION

  • Question 6
    Explain how would the involvement of local people be useful for successful management of forests. VIEW SOLUTION

  • Question 7
    Complete the following chemical equations :

    (i) CH3COOH + Na2CO3

    (ii) CH4 + O2

    (i) C2H5OH + Na → VIEW SOLUTION

  • Question 8
    Two carbon compounds X and Y have the molecular formula C3H6 and C4H10 respectively. Which one of the two is most likely to show addition reaction? Justify your answer. Also give the chemical equation to explain the process of addition reaction in this case.   VIEW SOLUTION

  • Question 9
    An element P (atomic number 20) reacts with an element Q (atomic number 17) to form a compound. Answer the following questions giving reason:

    Write the position of P and Q in the Modern Periodic Table and the molecular formula of the compound formed when P reacts with Q.  VIEW SOLUTION

  • Question 10
    Write the names given to the vertical columns and horizontal rows in the Modern Periodic Table. How does the metallic character of elements vary on moving down a vertical column? How does the size of atomic radius vary on moving left to right in a horizontal row? Give reason in support of your answer in the above two cases.  VIEW SOLUTION

  • Question 11
    Mention the total number of chromosomes along with the sex chromosomes that are present in a human female and a human male. Explain how in sexually producing organisms the number of chromosomes in the progeny remains the same as that of the parents.   VIEW SOLUTION

  • Question 12
    State the changes that take place in the uterus when:

    (a) Implantation of embryo has occurred.

    (b) Female gamete/egg is not fertilised.     VIEW SOLUTION

  • Question 13
    What happens when:

    (a) Accidently, Planaria gets cut into many pieces?

    (b) Bryophyllum leaf falls on the wet soil?

    (c) On maturation sporangia of Rhizopus bursts?  (3) VIEW SOLUTION

  • Question 14
    "Natural selection and speciation leads to evolution." Justify this statement.   VIEW SOLUTION

  • Question 15
    Differentiate between the acquired traits and the inherited traits in tabular form, giving one example for each.   (3) VIEW SOLUTION

  • Question 16
    A 3 cm tall object is placed 18 cm in front of a concave mirror of focal length 12 cm. At what distance from the mirror should a screen be placed to see a sharp image of the object on the screen. Also calculate the height of the image formed. VIEW SOLUTION

  • Question 17
    With the help of ciliary muscles, the human eye can change its curvature and thus alter the focal length of its lens. State the changes that occur in the curvature and focal length of the eye lens while viewing (a) a distance object, (b) nearby objects. 

    Explain, why a normal eye is not able to see distinctly the objects placed closer than 25 cm, without putting any strain on the eye.   VIEW SOLUTION

  • Question 18
    You have been selected to talk on 'ozone layer and its protection" in the school assembly on 'Environment Day.' 

    (a) Why should ozone layer be protected to save the environment?
    (b) List any two ways that you would stress in your talk to bring in awareness amongst your fellow friends that would also help in protection of ozone layer as well as the environment. VIEW SOLUTION

  • Question 19
    (a) Draw a ray diagram to explain the term angle of deviation.

    (b) Why do the component colours of incident white light split into a spectrum while passing through a glass prism, explain.

    (c) Draw a labelled ray diagram to show the formation of a rainbow.    (5) VIEW SOLUTION

  • Question 20
    Analyze the following observation table showing variation of image distance (v) with object distance (u) in case of a convex lens and answer the questions that follow, without doing any calculations: 
    S. No. Object distance u (cm) Image distance v (cm)
    1 −90 +18
    2 −60 +20
    3 −30 +30
    4 −20 +60
    5 −18 +90
    6 −10 +100

    (a) What is the focal length of the convex lens? Give reason in support of your answer.
    (b) Write the serial number of that observation which is not correct. How did you arrive at this conclusion?
    (c) Take an appropriate scale to draw a ray diagram for the observation at S. No. 4 and find the approximate value of magnification. VIEW SOLUTION

  • Question 21
    (a) To construct a ray diagram we use two rays which are so chosen that it is easy to know their directions after reflection from the mirror. List two such rays and state the path of these rays after reflection in case of concave mirrors. Use these two rays and draw ray diagram to locate the image of an object placed between pole and focus of a concave mirror.

    (b) A concave mirror produces three times magnified image on a screen. If the object is placed 20 cm in front of the mirror, how far is the screen from the object.  VIEW SOLUTION

  • Question 22
    Soaps and detergents are both types of salts. State the difference between the two. Write the mechanism of the cleansing action of soaps. Why do soaps not form lather (foam) with hard water? Mention any two problems that arise due to the use of detergents instead of soaps.  (5) VIEW SOLUTION

  • Question 23
    How do Mendel's experiments show that      (5)
    (a) traits may be dominant or recessive?
    (b) Inheritance of two traits is independent of each other? VIEW SOLUTION

  • Question 24
    (a) Name the organ that produces sperms as well as secretes a hormone in human males. Name the hormone it secretes and write its functions.

    (b) Name the parts of the human female reproductive system where fertilisation occurs.

    (c) Explain how the developing embryo gets nourishment inside the mother's body.      VIEW SOLUTION

  • Question 25
    Select the set of homologous organs from the following :   

    (a) Wings of pigeon and a butterfly

    (b) Wings of bat and a pigeon

    (c) Forelimbs of cow, a duck and a lizard

    (d) Wings of butterfly and a bat VIEW SOLUTION

  • Question 26
    A student while observing an embryo of a gram seed listed various parts of the embryo as listed below :   
    Testa, Micropyle, Cotyledon, Tegmen, Plumule, Radicle. On examining the list the teacher commented that only three parts are correct. Select these three correct parts :

    (a) Cotyledon, Testa, Plumule

    (b) Cotyledon, Plumule, Radicle

    (c) Cotyledon, Tegmen, Radicle

    (d) Cotyledon, Micropyle, Plumule VIEW SOLUTION

  • Question 27
    The correct sequencing of angle of incidence, angle of emergence, angle of refraction and lateral displacement shown in the following diagram by digits 1, 2, 3 and 4 is:  

    (a) 2, 4, 1, 3
    (b) 2, 1, 4, 3
    (c) 1, 2, 4, 3
    (d) 2, 1, 3, 4 VIEW SOLUTION

  • Question 28
    In the following diagram the correctly marked angles are :           

    (a) ∠A and ∠e

    (b) ∠i, ∠A and ∠D

    (c) ∠A ∠r and ∠e

    (b) ∠A ∠r and ∠D VIEW SOLUTION

  • Question 29
    If you focus the image of a distant object, whose shape is given below, on a screen using a convex lens,

    the shape of the image of this object on the screen would be:   



    (d)    VIEW SOLUTION

  • Question 30
    Three students A, B and C focused a distant building on a screen with the help of a concave mirror. To determine the focal length of the concave mirror they measured the distances as given below:  
    Student A : From mirror to the screen
    Student B : From building to the screen
    Student C : From building to the mirror
    Who measured the focal length correctly ;
    (a) Only A
    (b) Only B
    (c) A and B
    (d) B and C VIEW SOLUTION

  • Question 31
    For demonstrating the preparation of soap in the laboratory which of the following combinations of an oil and a base would be most suitable?

    (a) Mustard oil and calcium hydroxide

    (b) Castor oil and calcium hydroxide

    (c) Turpentine oil and sodium hydroxide

    (d) Mustard oil and sodium hydroxide    (1) VIEW SOLUTION

  • Question 32
    A student took four test tubes P, Q, R and S and filled about 8 mL of distilled water in each. After that he dissolved an equal amount of Na2SO4 in P, K2SO4 in Q, CaSO4 in R and MgSO4 in S. On adding an equal amount of soap solution and shaking each test tube well, a good amount of lather will be obtained in the test tubes:   (1)

    (a) P and Q
    (b) P and R
    (c) P, Q and S
    (d) Q, R and S VIEW SOLUTION

  • Question 33
    You have four test tubes, A, B, C and D containing sodium carbonate, sodium chloride, lime water and blue litmus solutions respectively. Out of these the material of which test tube/ test tubes would be suitable for the correct test of acetic/ethanoic acid?   
    (a) only A
    (b) A and B
    (c) B and C
    (d) A and D VIEW SOLUTION

  • Question 34
    A student places a candle flame at a distance of about 60 cm from a convex lens of focal length 10 cm and focuses the image of the flame on a screen. After that he gradually moves the flame towards the lens and each time focuses the image on the screen. 

    (a) In which direction-toward or away from the lens, does he move the screen to focus the image?
    (b) How does the size of the image change?
    (c) How does the intensity of the image change as the flame moves towards the lens?
    (d) Approximately for what distance between the flame and the lens, the image formed on the screen is inverted and of the same size? VIEW SOLUTION

  • Question 35
    A gas is liberated immediately with a brisk effervescence, when you add acetic acid to sodium hydrogen carbonate powder in a test tube. Name the gas and describe the test that confirms the identity of the gas.    VIEW SOLUTION

  • Question 36
    Name the type of asexual reproduction in which two individuals are formed from a single parent and the parental identity is lost. Write the first step from where such a type of reproduction begins. Draw first two stages of this reproduction.  (2) VIEW SOLUTION
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