Q25 of 30 Page 1

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.


(i) 2HgO → 2Hg + O2

(ii)


(iii) 4Al + 3MnO2→ 2Al2O3 + 3Mn


(iv) FeO3 + 2Al → 2Fe + Al2O3


(v) ZnCO3→ ZnO + CO2


OR


Mg + Cl2→ MgCl2



(II)  Ionic compounds: are formed when atoms of different charges (i.e. positive and negative ions) come together and transfer electron. These ionic bonds are typically very strong due to the high attractive forces holding the positively and negatively charged ions together (called electrostatic forces of attraction).


(III)


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23

Give reasons for the following:

(i) There is either a convergence or a divergence of magnetic field lines near the ends of a current carrying straight solenoid.


(ii) The current carrying solenoid when suspended freely rests along a particular direction.


(iii) The burnt out fuse should be replaced by another fuse of identical rating.


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(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.


 26

(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



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?