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Board Paper of Class 10 2017 Science (SET 3) - 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

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

  • Question 2
    What is fertilisation? Where does it occur in a human female?   VIEW SOLUTION

  • Question 3
    List any two abiotic components of an ecosystem.  VIEW SOLUTION

  • Question 4
    Redraw the following diagram on your answer-sheet and show the path of the reflected ray. Also mark the angle of incidence (∠i) and the angle of reflection (∠r) on the diagram.


  • Question 5
    Suggest any two ways by which the balance between the environment and industrial development is maintained so as to help undisturbed survival of the organisms on the Earth.  VIEW SOLUTION

  • Question 6
    Where and how did "Chipko Andolan" start in our country? How did this movement ultimately benefit the local people?  VIEW SOLUTION

  • Question 7
    Explain, giving reason, why carbon neither forms C4+ cations nor C4− anions, but forms covalent compounds which are bad conductors of electricity and have low melting point and low boiling point.    VIEW SOLUTION

  • Question 8
    What are hydrocarbons? Write the general formula of (i) saturated hydrocarbons, and (ii) unsaturated hydrocarbons and draw the structure of one hydrocarbon of each type.   VIEW SOLUTION

  • Question 9
    Why is atomic number considered to be a more appropriate parameter than atomic mass for the classification of elements in a periodic table? How does the metallic character of elements vary as we move (i) from left to right in a period, and (ii) top to bottom in a group in the modern periodic table? Give reasons to justify your answers.  VIEW SOLUTION

  • Question 10
    The atomic number of an element is 12.  (3)

    (a) Write its electronic configuration and determine its valency.

    (b) Is it more reactive or less reactive than Ca (atomic number 20)? Justify your answer giving reason.

    (c) Is it a metal or a non-metal?

    (d) Write the formula of its oxide. VIEW SOLUTION

  • Question 11
    Name the two types of mammalian gametes. How are these different from each other? Name the type of reproduction they are involved in. Write the advantage of this type of reproduction.  VIEW SOLUTION

  • Question 12
    How do variations arise in organisms? "Variation is useful for the survival of species." Justify this statement with the help of an example.  (3) VIEW SOLUTION

  • Question 13
    What is contraception? Name any two methods. How does the use of these methods have a direct effect on the health and prosperity of a family? State any three points.   VIEW SOLUTION

  • Question 14
    List any three factors and mention how they could lead to the rise of a new species.  VIEW SOLUTION

  • Question 15
    What are fossils? How do they act as an evidence for organic evolution?  VIEW SOLUTION

  • Question 16
    The magnification of an image formed by a lens is −1. If the distance between the object and its image is 60 cm, what is the distance of the object from the optical centre of the lens? Find the nature and focal length of the lens. If the object is displaced 20 cm towards the optical centre of the lens, where would the image be formed and what would be its nature? Draw a ray diagram to justify your answer.   VIEW SOLUTION

  • Question 17
    Using the phenomenon of scattering of light, explain why there is a difference in the colour of the sun as it appears during sunrise and at noon.   (3) VIEW SOLUTION

  • Question 18
    Your mother always thought that fruit juices are very healthy for everyone. One day she read in the newspaper that some brands of fruit juices in the market have been found to contain certain level of pesticides in them. She got worried as pesticides are injurious to our health.
    (a) How would you explain to your mother about fruit juices getting contaminated with pesticides?
    (b) It is said that when these harmful pesticides enter our body as well as in the bodies of other organisms they get accumulated and beyond a limit cause harm and damage to our organs. Name the phenomenon and write about it.  VIEW SOLUTION

  • Question 19
    What are fossils? How are fossils formed and how is their age determined? State the importance of fossils in the study of evolution.  VIEW SOLUTION

  • Question 20
    Give one example each of unisexual and bisexual flowers. Differentiate between the two types of pollination that occur in flowers. What happens when a pollen lands on a suitable stigma? Write about the events that occur till the seed formation in the ovary.  VIEW SOLUTION

  • Question 21
    What are esters? How are esters prepared? Write the chemical equation for the reaction involved. What happens when an ester reacts with sodium hydroxide? Write the chemical equation for the reaction and also state the name and use of this reaction.    VIEW SOLUTION

  • Question 22
    (a) Write the functions of each of the following parts of the human eye:
    (i) Cornea
    (ii) Iris
    (iii) Crystalline (Eye) lens
    (iv) Ciliary muscles
    (v) Retina

    (b) A person is unable to see distinctly the objects closer than 1 m. Name the defect of vision he is suffering from. Draw ray diagrams to illustrate the cause of the defect and its correction by suitable lens.  VIEW SOLUTION

  • Question 23
    Analyse 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)
    v (cm)
    1 –60 +12
    2 –30 +15
    3 –20 +20
    4 –15 +30
    5 –12 +60
    6 –9 +90

    (a) What is the focal length of the convex lens? State reason for your answer.
    (b) For what object-distance (u) is the corresponding image-distance (v) not correct? How did you arrive at this conclusion?
    (c) Choose 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 24
    (a) Define the following terms in the context of spherical mirrors : 
    (i) Pole

    (ii) Centre of curvature

    (iii) Radius of curvature

    (iv) Principal axis

    (b) Draw ray diagrams to show the principal focus of (i) a concave mirror, and (ii) a convex mirror.

    (c) In the following diagram. MM' is a concave mirror and AB is an object. Draw on your answer-sheet a ray diagram to show the formation of image of this object.


  • Question 25
    In the following diagram, the correctly marked angles are  (1)

    (A) All
    (B) Only ∠i and ∠A
    (C) ∠i, ∠r and ∠A
    (D) ∠i, ∠A and ∠D VIEW SOLUTION

  • Question 26
    When you focus the image of a distant flag, whose shape is given below, on a screen using a convex lens, the shape of the image as it appears on the screen is 





  • Question 27
    An optical device has been given to a student and he determines its focal length by focusing the image of the sun on a screen placed 24 cm from the device on the same side as the sun. Select the correct statement about the device.  
    (A) Convex mirror of focal length 12 cm
    (B) Convex lens of focal length 24 cm
    (C) Concave mirror of focal length 24 cm
    (D) Convex lens of focal length 12 cm VIEW SOLUTION

  • Question 28
    Select from the following the best experimental set-up for tracing the path of a ray of light through a glass slab:

    (A) I

    (B) II

    (C) III


  • Question 29
    You are asked to prepare hard water in your laboratory. Select a group from the following groups of salts, any salt of which you may dissolve in distilled water to obtain hard water.  
    (A) NaCl; Na2SO4; KCl
    (B) NaCl; CaCl2; KCl
    (C) CaCl2; CaSO4; MgSO4

  • Question 30
    If you take some distilled water in a test-tube, add an equal amount of acetic acid to it, shake the test-tube well and leave it undisturbed on the test-tube stand, then after about 5 minutes what would you observe?
    (A) There is a layer of water over the layer of acetic acid.
    (B) A precipitate is setting at the bottom of the test-tube.
    (C) Bubbles of colourless gas are coming out of the test-tube.
    (D) There is a clear, colourless transparent solutions in the test-tube.   (1) VIEW SOLUTION

  • Question 31
    Which one of the following sets of materials can be used to prepare soap?  (1)

    (A) Neem oil and calcium hydroxide

    (B) Castor oil and sodium hydroxide

    (C) Mineral oil and sodium hydroxide

    (D) Neem oil and magnesium hydroxide VIEW SOLUTION

  • Question 32
    Choose the correct statement(s) on budding in yeast from the following :  (1)

    I. A parent cell divides into two or more daughter cells and here the parent identity is lost.

    II. In this the elongated nucleus divides to form two or more daughter nuclei.

    III. A bud arises from a particular region on a parent body.

    IV. After detaching from the parent body the bud grows into a new independent individual.

    (A) I only

    (B) III only

    (C) II and III only

    (D) III and IV only VIEW SOLUTION

  • Question 33
    Select a set of homologous organs from the following: 
    (A) Wings of a bat and wings of a butterfly
    (B) Wings of a pigeon and wings of a bat
    (C) Wings of a butterfly and wings of a pigeon
    (D) Forelimbs of a duck, forelimbs of a cow and forelimbs of a lizard VIEW SOLUTION

  • Question 34
    You have to perform the experiment, "To identify the different parts of an embryo of a gram seed." Describe the procedure that you would follow.  VIEW SOLUTION

  • Question 35
    Trace the path of a ray of light incident at an angle of 45° on a rectangular glass slab. Write the measure of the angle of refraction, the angle of emergence and the lateral displacement suffered by the ray as it passes through the slab.   (2) VIEW SOLUTION

  • Question 36
    (A) If you are asked to report your observations about the following two properties of acetic acid, what would you report?
    (i) Odour
    (ii) Effect on litmus

    (B) If you take a pinch of sodium hydrogen carbonate powder in a test-tube and add drop-by-drop acetic acid to it, what would you observe immediately? List any two main observations. VIEW SOLUTION
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