Q26 of 30 Page 1

(a) Compare soaps and detergents on the basis of their composition and cleansing action in hard water.

(b) What happens when ethanol is treated with sodium metal? State about the behaviour of ethanol in this reaction.


(c) Draw the structure of cyclohexane.


(d) Name the following compound



(a)


The sodium ion present in the soap react with the magnesium and calcium ions present in the hard water to form scum and therefore is not effective in the hard water whereas in the case of the detergent no scum formation takes place.


(b)



The nature of O-H bond in alcohol is polar and therefore , it easily loses hydrogen ion on coming in contact with the metal.


(c)



(d) Ethanal or Acetaldehyde


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24

(a) With the help of labelled ray diagram show the path followed by a narrow beam of monochromatic light when it passes through a glass prism.

(b) What would happen if this beam is replaced by a narrow beam of white light?


OR


(a) A person is suffering from both myopia and hypermetropia.


(i) What kind of lenses can correct this defect?


(ii) How are these lenses prepared?


(b) A person needs a lens of power + 3D for correcting his near vision and – 3D for correcting his distant vision. Calculate the focal lengths of the lenses required to correct these defects.


 25

Write balanced chemical equations to explain what happens, when

(i) Mercuric oxide is heated.


(ii) Mixture of cuprous oxide and cuprous sulphide is heated.


(iii) Aluminium is reacted with manganese dioxide.


(iv) Ferric oxide is reduced with aluminium.


(v) Zinc carbonate undergoes calcination.


OR


(i) By the transfer of electrons, illustrate the formation of bond in magnesium chloride and identify the ions present in this compound.


(ii) Ionic compounds are solids. Give reasons.


(iii) With the help of a labelled diagram show the experimental set up of action of steam on a metal.


 27

(a) Write the correct sequence of steps followed during journey of oxygen rich blood from lungs to various organs of human body.

(b) What happens when the system of blood vessels develops a leak?


 28

(a) Draw a diagram showing germination of pollen on stigma of a flower and mark on it the following organs/parts:

(i) Pollen Grain


(ii) Pollen tube


(iii) Stigma


(iv) Female germ cell


(b) State the significance of pollen tube.


(c) Name the parts of flower that develop after fertilization into


(i) Seed


(ii) Fruit


OR


(a) Use of a condom is beneficial for both the sexes involved in a sexual act." Justify this statement giving two reasons.


(b) How do oral contraceptive help in avoiding pregnancies?


(c) What is sex selective abortion? How does it affect a healthy society? (State any one consequence)