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GGN PUBLIC SCHOOL
ASSIGNMENT XII
CHEMISTRY
1 Copper crystallizes into a fcc lattice with edge length 3.61x10-8cm
Show that the calculated density is in agreement with its measured valueof
8.92 g cm-3
2 Explain the Metals excess defect with eg
3 Answer the following:
a) What is meant by a “colligative property”?
b) Why does the presence of a solute in a solvent depress its
freezing point?
c) The freezing point of pure nitro benzene is 278.8K. When
2.5gm of an unknown substance was dissolved in 100g of
nitro benzene,the freezing point of the solution was found to
be 276.8K.The freezing point depression constant of nitro benzene
is 8.0K kg/mol.Calculate the molar mass of the unknown solute.
4 Calculate the boiling point of a solution containing 0.61g of benzoic
acid in 5 g of CS2 .Assuming 84% dimerisation of acid. The boiling
point and Kb of CS2 are 46.2 0C and 2.3 K Kg mol-1 respectively.
5 A metal crystallizes into fcc with edge length 4.07x 10-8 cm and density is
10.5 g cm-3.calculate atomic mass.
6 A unit cell consist of a cube in which atoms B are at the corners & cations A
at the centre of the alternate faces of the unit cell. What is the simplest
formula of the compound?
7 Calculate the efficiency of packing in case of simple cubic metal crystal.
8 A metal crystallizes into cubic face centered and body centered whose unit
cell edge length are 3.5 A & 3.5 A respectively. Calculate the ratio of densities
of fcc and bcc
9 Derive an equation to express the relative lowering of vapour
pressure for a solution is equal to the mole fraction of the solute in
it when the solvent alone in volatile.
10 1.00g of non-electrolyte dissolved in 50.5g of benzene lowered
the freezing point of benzene by 0.40 K. the freezing point
depression constant of benzene is 5.12K Kg mole-1. Find the molar
mass of the Solute.
1 Account for the following:
1 What is basicity of phosphoric acid & why?
2 PCl3 fumes in moist air.
3 conc. H2SO4 is a strong dehydrating agent.
4 of noble gases , only xenon is known to form real chemical compound
2 Explain mechanism of dehydration of alcohol for formation of 1) ethers
2)alkene
3 Suggest a reason for the large difference in the boiling points of butanol
and Diethylether although they have same solubility in water
4
30 Account the following
(a) Flourine shows -1 oxidation states whereas halogens show
+1,+3,+5,+7oxidation states
(b)Bond dissociation energy of F2 is less than Cl2
(c)SO3 is not added to to H2O to get H2SO4.
( d) what is covalency of nitrogen in NH4+
(e) why does OF6 not exist ?
5
A greenish yellow gas with pungent and suffocating odour is
manufactured by Deacons process . identify this gas . and write reactions
of this gas with NaoH.
6 Why is helium used in diving apparatus?
7 Why has it been difficult to study the chemistry of radon?
8 Draw structure of 1) H2S2O7 2)HClO3 3) IF7 4) XeO3
9 Describe manufacturing of H2SO4 by contact process.
10 Why are halogens coloured?
11 Explain 1) halogenations of phenol
2) reaction to distinguish between 1 , 2 and 3 alcohols
12 An aqueous solution of a gas (X) shows following reactions:
It turns red litmus blue.When added in excess to a copper sulphate solution, a deep
blue colour is obtained.On addition of ferric chloride solution a brownish precipitate
soluble in HNO3 is obtained. Identify (X) and give equations for the reactions in step
(ii) and (iii)
13 . Write reaction of but-1-ene with hydrogen bromide in presence of
hydrogen peroxide.
14 Why are alcohols soluble in water?
15 (a)Which have higher melting point
1-chlorobutance or 2-chloro-2-methypropane
(b) Why does benzyl chloride undergo nucleophilic substitution faster than
Chlorobenzene. Explain giving the resonating structure .