Q18 of 47 Page 1

Give reasons for the following:

a. Dioxygen is a gas but sulphur a solid.


b. NO (g) released by jet aeroplanes is slowly depleting the ozone layer.


c. Interhalogens are more reactive than pure halogens.


a.Oxygen has a tendency to form pπ-pπ multiple bond due to absence of d-orbitals and high bond dissociation enthalpy. So, dioxygen exists as a gas. But on the other hand Sulphur has tendency to form single bond due to the presence of d-orbitals and thus exists in polyatomic (S8)form.


b. NO (g) released by jet aeroplanes is slowly depleting the ozone layer because it reacts with ozone to form NO2 and O2


NO + O3 → NO2 + O2


c. Interhalogens are more reactive than pure halogens because interhalogen bonds are weaker than bonds in pure halogens, i.e., X -X' bond is weaker than X-X bond


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A solution 0.1 M of Na2SO4 is dissolved to the extent of 95%. What would be its osmotic pressure at 27oC? (R = 0.0821 L atm K-1 mol-1)

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Write down the reactions taking place in blast furnace related to the metallurgy of iron in the temperature range 500 K – 800 K. What is the role of limestone in the metallurgy of iron?

OR


What happens when


a. Silver is leached with NaCN in the presence of air?


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c. NaCN is added in an ore containing PbS and ZnS during concentration by froth floatation method?


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Write the structures of monomers used to obtain the following polymers:

a. Neoprene


b. PHBV


c. Bakelite


OR


a. Arrange the following polymers in decreasing order of their intermolecular forces :
Bakelite, Polythene, Buna-S, Nylon-6,6


b. Write the monomers of the following polymer :


c. What is the structural difference between high density polythene (HDP) and low density polythene (LDP)?


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a. Why are metal hydroxides better alternatives than sodium hydrogencarbonate in antacids?

b. Why is aspirin used in the prevention of heart-attacks?


c. Why antihistamines do not affect the secretion of acid in stomach?


OR


Define the following terms with a suitable example of each :


a. Tranquilizers


b. Antibiotics


c. Non-ionic detergents