X SCIENCE SA II 3 & 5 MARKS SAMPLE PAPER 3

14.    A needle placed 45 cm from a lens forms an image on a screen placed 90 cm on the other side of the lens. Identify the type of lens. Determine its focal length and the power. What is the size of image if, needle is        5 cm in height?

15.    A person wears spectacles of power - 2.5 D.  Name the defect of vision he is suffering from.  Draw the  ray  diagram for

(i)      the defective eye                      (ii)     its correction after using a suitable lens

16.    (a)     For the same  angle  of incidence 45° , the  angle  of refraction in two  transparent  media;  I and  II is 20° and  30° respectively. Out of I and II, which medium is optically denser and why?

(b)     Light enters from air to diamond which has refractive index of 2.42.   Calculate the speed of light in diamond, if speed of light in air is 3.00 X 10⁸ m/s

17.    An organic compound A is widely used as a preservative in pickles and has a molecular formula C₂H₄O₂. This  compound reacts  with  ethanol to  form  a sweet  smelling compound B;

(a)     Identify the compound A.

(b)     Write the chemical equation for its reaction with ethanol to form compound B.

(c)     How can we get compound A back from B?

18.    (1)     The elements of the second period along with their atomic number in parentheses are given  below:

   B (5), Be (4), O (8), N (7), Li (3), C (6), F (9)

(a)              Arrange them in the same order as they are in the periodic table.

(b)              Which element has the (i) largest (ii) smallest atom?

(2)     Why does the atomic radius change as we move from left to right in a period?

19.    (a)     Draw  a flow  chart  to determine the characteristics of the progeny of a cross between Tall Pea plants with  Short  Pea plants showing

(i)      F1 Generation

(ii)     F2 Generation.

(b)     List the Dominant and Recessive characters.

20.    (a)     Differentiate between :                                                                                                              

(i)      Homologous organs and Analogous organs

(ii)     Pollination and Fertilization

(b)     What do fossils tell us about the process of evolution?

21.    Justify giving reasons how human male only is responsible for the sex of a new born child and female has no role in it.

22.    (a)     Explain giving examples how artificial selection has helped in the formation of newer varieties of caulis flower.

(b)     List the steps involved in the formation of new species.

(c)     How different races of human beings belong to the same species?

23.     (i)      Under what condition, a concave mirror produces a virtual and magnified image? Draw a labelled ray diagram to show the formation of image in the above case. Also state the position of object to produce magnified and real image.

(ii)     A ray of light moving along principal axis is falling on a concave mirror. Draw the path of reflected ray. Also state the values of angle of incidence and reflection in this case.

OR

(i)      Where should an object is placed in case of a convex lens to form an image of same size as of the object. Show with the help of a ray diagram the position and nature of the image formed.

(ii)     With the help of ray diagram, illustrate the change in position, nature and size of the image formed if the convex lens in case (i) is replaced by concave lens of same focal length.

(iii)    State the condition under which a light ray passes undeviated through a lens.

24.    (a)     Write chemical equations along with necessary condition for the following changes to take  place  :

(i)      Ethanol to Ethanoic acid.

(ii)     Ethanoic acid to Sodium acetate. (iii)    Methane to Chloromethane.

(b)     What is a homologous series of organic compounds?  Explain it with an example.

OR

(a)        Complete the following reactions stating the main products formed in each.

(i)       CH₃ – CH₂ = CH₂    +  H₂ 

(ii)     C₂H₅OH + NaOH →

(iii)    CH₃  COOH  + Na₂CO₃ →

(b)     Write  the  next  homologue  of  propanol (CH₃CH ₂CH₂OH)  and   Butanal (CH₃CH₂CH₂CHO)

25.    (a)   Draw  neat  labelled diagram of human female  reproductive system.                        

(b)  Name  one organ  each in the body  of Male and  Female  reproductive system that plays  a role of endocrine gland along  with  the production of germ  cells. Name one  hormone in each  case.

(c)   Name  the part  where the fertilization of gametes takes  place  and  also the place where the fertilized egg is implanted.

OR

(a)    Draw  a neat  labelled diagram of pistil  showing fertilization of pollen  on stigma.

(b)    Give the functions of : (i) stigma  (ii) ovary

(c)     State in brief the formation of seed  in a flower.