What is meant by positive and negative deviations from
Raoult's law and how is the sign of related
to positive and negative deviations from Raoult's law? [2]
(i) Extraction of Au by leaching with NaCN involves both
oxidation and reduction.
Justify by giving equations for the reactions involved.
(ii) Why is froth floatation method selected for the
concentration of sulphide ores? [2]
Account for the following.
(i) Aniline does not undergo Frieda-Crafts reaction.
(ii) Gabriel phthalimide synthesis is preferred for synthesizing
primary amines. [1]
Out of ,andwhich
is more easily hydrolysed by aqueous KOH? Give
reason.
[2]
Or
The treatment of alkyl chlorides with aqueous KOH leads to
the formation of alcohols, but in presence of alcoholic KOH, alkenes are major
products. Explain. [2]
Silver crystallises with face-centred cubic unit cell.
Each side of this unit cell has a length of 409 pm. What is the radius of
silver atom? Assume the atoms just touch each other on the diagonal across the
face of the unit cell. [3]
Or
Aluminium crystallises in a cubic close packed structure.
Radius of the atom in the metal is 125 pm.
(i) What is the length of the side of the unit cell?
(ii) How many unit cells are there in 1cm3 of
aluminium? [3]
0.6 mL of acetic acid ()
having density 1.06 g is
dissolved in 1 litre of water. The depression in freezing point observed for
this strength of acid was 0.0205°C. Calculate the van't Hoff factor and the
dissociation constant of acid. [3]
There is growing interest in the use of chelate therapy in
medicinal chemistry. An example is the treatment of problems caused by the
presence of metals in toxic proportions in plant/animal systems. Detection of
cations through coloured complex formation is done in qualitative analysis.
Read the above passage and answer the following questions.
(a) Name the chelating agents that can remove copper, iron
and lead from water, [1]
(b) Name the compound that inhibits the growth of
tumours. [1]
(c) Recent studies show that cis-platin can cause serious
side effects; including severe kidney damage. What is the alternative
medicine? [1]
(i) Using valence bond theory, predict the geometry and
magnetic character of .
(ii) Among octahedral and tetrahedral crystal fields, in
which case the magnitude of crystal field splitting is larger? [1]
Give reasons for the following observations.
(a) Peptizing agent is added to convert precipitate into
colloidal solution.
(b) Cottrell's smoke precipitator is fitted at the mouth
of chimney used in factories.
(c) Colloidal gold is used for intramuscular
injection. [3
x 1]
Explain the following.
(i) MnO is basic while is
acidic in nature.
(ii) Chromium is a typical hard metal but mercury is a
liquid.
(iii) The transition metals form a large number of complex
compounds.
(iv) The highest oxidation state of a metal is exhibited
in its oxide or fluoride only.
(v) E° value for the couple
is much more positive than that foror[5x1]
Or
(i) Complete the following reactions.
(a) (b)
(ii)Which of the following has the maximum number of
unpaired electrons?
(iii) Give two consequences of lanthanide contraction.
(iv) Based on the data, arrange and in the
increasing order of stability of + 2 oxidation state.
(v) Calculate spin only magnetic moment of []
The following data were obtained during the first order
thermal decomposition of at a
constant volume
Experiment
time
Total
pressure (atm)
I
II
0
100
0.5
0.6
Calculate the rate constant of the reaction when total pressure is 0.65
atm. [5]
Or
(a) For the given reaction,
If , what
is the value of
(b) Sucrose decomposes in acid solution into glucose and
fructose according to the first order rate law with hrs.
Calculate the fraction of sucrose which remains after 8 hrs.
(c) For a chemical reaction variation in concentration In [R]
vs time (min) plot is shown below.
(i) What is the order of the reaction?
(ii) What are the units of rate constant, k for the
reaction? [1+3+1]
(a) An organic compound (A) with the molecular formula forms
2, 4-DNP derivative reduces Tollen's reagent and undergoes Cannizzaro reaction.
On vigorous oxidation it gives 1,2-benzene dicarboxylic acid. Identify the compound
(A).
(b) Give simple chemical tests to distinguish between the
following pairs of compounds.
(i) Phenol and benzoic acid (ii)
Benzaldehyde and acetophenone. [3 + 3]
Or
(a) Predict the products of the following reactions.
(i)
(ii)
(iii)
(b) Describe the following giving linked chemical
equations.
(i) Aldol condensation (ii)
Stephen reaction [3
+ 2]