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  1. Asked: In:

    What happens when he moves the object very close to the lens?

    shamlal

    No image on the screen.

    No image on the screen.

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  2. Asked: In:

    What happens to the size of image – does it increase or decrease?

    shamlal

    Increases

    Increases

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  3. Asked: In:

    In which direction – towards or away from the lens, does he move the screen to focus the object?

    shamlal

    Away from the lens

    Away from the lens

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  4. Asked: In:

    List two observations which you make when you add a pinch of sodium hydrogen carbonate to acetic acid in a test tube. Write chemical equation for the reaction that occurs.

    Best Answer
    shamlal

    (l) Brisk effervescence (ii) Evolution of a colourless gas NaHCO3 + CH3COOH ------- CH3COONa + H2O + CO2

    (l) Brisk effervescence
    (ii) Evolution of a colourless gas
    NaHCO3 + CH3COOH ——- CH3COONa + H2O + CO2

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  6. Asked: In:

    Four students P, Q, R and S traced the path of a ray of light passing through a glass slab for an angle of incidence of 40″ and measured the angle of refraction. The values as measured by them were 18″, 22″;25″ and 30″ respectively. The student who has performed the experiment methodically is

    shamlal

    (c) R

    (c) R

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  7. Asked: In:

    Four students A, B, C and D reported the following set of organs to be homologous. Who is correct?

    shamlal

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

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

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  8. Asked: In:

    A student has obtained a point image of a distant object using the given convex lens. To find the focal length of the lens he should measure the distance between the:

    shamlal

    (b) lens and the screen only

    (b) lens and the screen only

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  9. Asked: In:

    A student prepared 20% sodium hydroxide solution in a beaker to study saponification reaction. Some observations related to this are given below:

    shamlal

    Sodium hydroxide solution turns red litmus blue Sodium hydroxide readily dissolves in water The beaker containing solution appears cold when touched from outside

    Sodium hydroxide solution turns red litmus blue

    Sodium hydroxide readily dissolves in water
    The beaker containing solution appears cold when touched from outside

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  11. Asked: In:

    A student adds a small quantity of caustic soda to a test tube containing 2 mL of distilled water. He then shakes the test tube well and leaves it to settle for some time. After about 5 minutes he observes that in the test tube there is:

    shamlal

    (a) a clear transparent colourless solution

    (a) a clear transparent colourless solution

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  12. Asked: In:

    Write the functions of the following in human female reproductive system: Ovary, Oviduct, Uterus How does the embryo get nourishment inside the mother’s body? Explain in brief.

    Best Answer
    shamlal

    Functions: Ovary: (l) Production of female hormone/oestrogen and progesterone. (ii) Production of female gamete,/egg/germ cell. Oviduct: (l) Transfer of female gamete from the ovary. (ii) Site of fertilization. Uterus: (l) Implantation of Zygote/embryo. (ii) Nourishment of developing embryo. . PlaceRead more

    Functions:
    Ovary: (l) Production of female hormone/oestrogen and progesterone.
    (ii) Production of female gamete,/egg/germ cell.
    Oviduct: (l) Transfer of female gamete from the ovary.
    (ii) Site of fertilization.
    Uterus: (l) Implantation of Zygote/embryo.
    (ii) Nourishment of developing embryo.
    . Placenta is a special disc like tissue embedded in the mother’s uterine wall and connected to the foetus/embryo.

    .Placenta provides a large surface area for glucose and oxygen/nutrients to pass from the mother’s blood to the embryo/foetus.

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