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Class XII: Assignment of p-Block and d & f-Block elements
P-block
Complete the following reactions :
(ii) N4H Cl (aq)
+ NaNO2
(aq)
¾¾®
2. (i) NH2CONH2 + H2O ¾¾®
(ii) FeCl3 (aq) + NH4OH ¾¾®
3. (i) Ca3 P2 + H2 O (l) ¾¾®
(ii) I2 + HNO3 (conc.) ¾¾®
4. (i) Ba(N3)2¾¾heat®
(ii) 4H3PO3¾¾heat®
5. (i) PH4I + KOH ¾¾®
(ii) HgCl2 + PH3 ¾¾®
6. (i) PCl3 + 3H2O ¾¾®
(ii) S + H2SO4 (conc.) ¾¾®
7. (i) Al2O3(s) + NaOH
(aq) + H2O(l) ¾¾®
(ii) HCl + O2 + CuCl¾¾¾¾®
8. (i) Ca(OH)2 + Cl2 ¾¾®
(ii) XeF4 + H2O ¾¾®
9. (i) Na2SO3 + Cl2 + H2O ¾¾®
(ii) NaHCO3 + HCl¾¾®
10. (i) XeF6 + H2O Completehydrolysis¾¾¾¾®
(ii) XeF6 + H2OPartialhydrolysis
¾¾¾¾®
11. (i) NO3– + Fe2+ + H+ ¾¾®
(ii) Zn + HNO3 (dil) ¾¾®
12. (i) Zn + HNO3 (conc) ¾¾®
(ii) P4 + HNO3 (conc) ¾¾®
13. (i) NH3 + O2¾¾Pt/Rh®
(ii) P4 + NaOH + H2O ¾¾®
14. (i) P4 + SOCl2 ¾¾®
(ii) P4 + SO2Cl2 ¾¾®
15. (i) PbS + O3 ¾¾®
(ii) KI + H2O + O3 ¾¾®
16. (i) MnO4– + SO2 + H2O ¾¾®
(ii) Zn + HNO3(dil)¾¾®
17. (i) NH3 (Excess) +
Cl2
¾¾®
(ii) NH3 + Cl2 (Excess) ¾¾®
18. (i) Cl2 + NaOH
(cold and dil) ¾¾®
(ii) Cl2 + NaOH
(hot &conc) ¾¾®
19. (i) Fe + HCl¾¾®
(ii) Cl2 + F2 (Excess) ¾¾®
20. (i) U + ClF3 ¾¾®
(ii) FeSO4 + H2SO4 + Cl2 ¾¾®
21. (i) How is HNO3 prepared
commercially?
(ii) Write chemical equations
of the reactions involved.
(iii) What
concentration by mass of HNO3 is obtained?
22. (i) How does O3 react with
lead sulphide? Write chemical equation.
(ii) What happens
when SO2
is
passed in acidified KMnO4 solution?
23. An unknown salt X
reacts with hot conc. H2SO4 to produce
a brown coloured gas which intensifies on addition on copper turnings. On
adding dilute ferrous sulphate solution to an aqueous solution of X and then
carefully adding conc. H2SO4 along the
sides of the test tube, a brown complex Y is formed at the interface between
the solution and H2SO4. Identify X and
Y and write the
chemical equation involved in the reaction.
24.A transluscent
while waxy solid (A) on heating in an inert atmosphere is converted to its
allotropic form (B), Allotrope (A) on reaction with very dilute aqueous NaOH
liberates a highly poisonous gas (C) having a rotten fish smell, with excess of
chlorine forms D which hydrolyses to form compound (E). Identify the compounds
(A) to (E).
25. Write balanced
equation for the following reactions :
(a) Zn is treated
with dilute HNO3.
(b) NaCl is heated
with H2SO4 in the
presence of MnO2.
(c) Iodine is treated
with conc. HNO3.
25. X2 is a
greenish yellow gas with pungent offensive smell used in purification of water.
It partially dissolves in H2O to give a solution which turns
bluelitmus red. When X2 is passed through NaBr Solution, Br2 is
obtained.
(a) Identify X2, name the
group to which it belongs.
(b) What are the
products obtained when X2 reacts with H2O?
Writechemical equation.
(c) What happens when
X2
reacts
with hot and conc. NaOH? Giveequation.
26.How is PH3 prepared
in the laboratory? How is it purified? How does the solution of PH3 in water
react on irradiation with light and on absorption in CuSO4? How can
you prove that PH3 is basic in nature?Write the chemical
equations for all the reactions involved.
27. A white waxy,
translucent solid, M, insoluble in water but soluble in CS2,glows in
dark. M dissolves in NaOH in an inert atmosphere giving a poisonous gas (N).
Also M catches fire to give dense white fumes of Q :
(a) Identify M, N and
Q and write the chemical equations of the reactions involved.
(b) M exists in the
form of discrete tetrahedral molecules. Draw its structure.
(c) M on heating at
573 K is changed into other less reactive form, Q, which is non-poisonous,
insoluble in water as well as in CS2 and does not glow in
dark, Identify Q and draw its structure.
D
& F- block
1.The stability of Cu2+ (aq) is
more than that of Cu+ (aq). Why?
2. Indicate the steps
in the preparation of
(a) K2Cr2O7 from
Chromite ore.
(b) KMnO4 from
Pyrolusite ore.
3.(a) Why do
transition metals show high melting points?
(b) Out of Fe and Cu,
which one would exhibit higher melting point?
4. Describe giving
reason which one of the following pairs has the property
indicated :
(a) Cr2+ or Fe2+ (stronger
reducing agent).
(b) Co2+ or Ni2+ (lower
magnetic moments).
5. Of the ions Co2+, Sc3+, Cr3+ which one
will give colourless aqueous solution and how will each of them respond to magnetic
field and why?
6. For the first row
transition metals the enthalpy of atomisation value are :
ScTi V
Cr Mn Fe
Co Ni Cu
Zn
∆aH/kJ mol–1 326 473
515 397 281 416 425 430 339 126
Assign reason for the
following :
(a) Transition elements
have higher values of enthalpies of atomisation.
(b) The enthalpy of
atomisation of zinc is the lowest in 3d - series.
7. Account for the
following :
(a) Copper shows its
inability to liberate hydrogen gas from the dilute acids.
(b) Scandium (Z = 21)
does not exhibit variable oxidation states.
8. Copper (I)
compounds undergo disproportionation. Write the chemical equation for the
reaction involved and give reason.
9.Account for the
following :
(a) La(OH)3 is more
basic than Lu(OH)3
(b) Zn2+ salts are white.
(c) Cu(I) compounds
are unstable in aqueous solution and undergodisproportination.
10. Describe the
oxidising action of potassium dichromate with following. Writeionic equations
for its reaction with.(a) Iodide ion (b) Iron (II) (c) H2S.
11. (a) Deduce the
number of 3d electrons in the following ions :
Fe3+, Cu2+ and Sc3+.
(b) Why do transition
metals form alloys.
(c) Write any two
characteristics of interstitial compounds.
12.(a) For M2+/M and M3+/M2+ systems,
the Evalues for some
metals are as follows :
Cr2+/Cr = –
0.9V and Cr3+/Cr2+ = – 0.4V
Mn2+/Mn = –
1.2 V and Mn3+/Mn2+ = + 1.5V
Fe2+/Fe = –
0.4V and Fe3+/Fe2+ = + 0.8V
Use this data to
comment upon :
(i) the stability of
Fe3+
in
acid solution as compared to that of Cr3+ and Mn3+
(ii) the ease with
which iron can be oxidised as compared to a similar process for either chromium
or manganese.
(b) How is the
variability in oxidation states of transition metals different from that of the
non-transition metals? Illustrate with examples.
13.When a white
crystalline compound A is heated with K2Cr2O7 and conc.H2SO4, a
reddish brown gas B is evolved, which gives a yellow coloured solution C when
passed through NaOH. On adding CH3COOH and(CH3COO)2 Pb to
solution C, a yellow coloured ppt. D is obtained. Also on heating A with NaOH
and passing the evolved gas through K2HgI4 solution,
a reddish brown precipitate E is formed.Identify A, B, C, D and E and write the
chemical equations for the reactions involved.
14.A green compound
‘A’ on fusion with NaOH in presence of air forms yellow compound ‘B’ which on
acidification with dilute acid, gives orange solution of compound ‘C’. The
orange solution when reacted with equimolarammonuim salt gives compound ‘D’
which when heated liberates nitrogen gas and compound ‘A’. Identify compounds A
to D and write the chemical
equation of the
reactions involved.
[Hint :‘A’ =
CrO3; ‘B’ = Na2CrO4; ‘C’ = Na2Cr2O7 ‘D’ = (NH4)2 Cr2O7
15. Assign reasons
for the following :
(a) There is no
regular trends in E° values of M2+/M systems in 3d series.
(b) There is gradual
decrease in the ionic radii of M2+ ion in 3d series.
(c) Majority of
transition metals form complexes.
(d) Ce3+ can be
easily oxidised to Ce4+
(e) Tantalum and
palladium metals are used to electroplate coinage metals.
16. Account for the
following :
(a) Actinoids display
a variety of oxidation states.
(b) Yb2+ behaves as
a good reductant.
(c) Cerium (iv) is a
good analytical reagent.
(d) Transition metal
fluorides are ionic in nature while chlorides and bromides are covalent in
nature.
(e) Hydrochloric acid
attacks all the actinoids.
17. Explain by giving
suitable reason :
(a) Co(II) is stable
in aqueous solution but in the presence of complexing agent it is readily
oxidised.
(b) Eu2+, Yb2+ are good
reductants whereas Tb4+ is an oxidant.
(c) AgCl dissolves in
ammonia solution
(d) Out of Cr2+ or Fe2+, which
one is a stronger reducing agent?
(e) The highest
oxidation state is exhibited in oxoanions of a transition metal.
Class XII: Ouestions of Chapter - 10 & 11 (Organic Chemistry)
1. An alcohol A (C4H10O) on
oxidation with acidified potassium dichromategives carboxylic acid B (C4H8O2).
Compound A when dehydrated withconc. H2SO4 at 443 K
gives compound C. Treatment of C with aqueousH2SO4 gives compound
D (C4H10O) which
is an isomer of A. CompoundD is resistant to oxidation but compound A can be
easily oxidised. Identify
A, B, C and D and
write their structures.
2. An organic
compound A having molecular formula C6H6O gives
acharacteristic colour with aqueous FeCl3. When A
is treated with NaOHand CO2 at 400 K under pressure, compound B is
obtained. CompoundB on acidification gives compound C which reacts with acetyl
chloride to
form D which is a
popular pain killer. Deduce the structure of A, B, C andD. What is the common
name of Drug D?
3. An ether A (C5H12O) when
heated with excess of hot concentrated HIproduced two alkyl halides which on
hydrolysis from compounds B and C.Oxidation of B gives an acid D whereas
oxidation of C gave a ketone E.Deduce the structures of A, B, C, D and E.
4. Phenol, C6H5OH when it
first reacts with concentrated sulphuric acid, formsY.Y is reacted with
concentrated nitric acid to form Z. Identify Y and Z andexplain why phenol is
not converted commercially to Z by reacting it withconc. HNO3.
5. Give reason for
the following:
(i) The C–O–C bond
angle in dimethyl ether is (111.7°)
(ii) Alcohols have
higher boiling points than ethers of comparablemolecular masses.
(iii) Phenols are
more acidic than alcohols.
(iv) Nitro phenol is
more acidic than o-methoxyphenol.
(v) Phenol is more
reactive towards electrophilic substitution reactionthan benzene.
(vi) The following is
not an appropriate method for the preparation of1-methoxy-4-nitrobenzene;
(vii) Write the
suitable reaction for the preparation of1–methoxy–4–nitrobenzene
(viii) o-nitrophenol
is steam volatile but p-nitrophenol is not.
(ix) phenol is less
polar than ethanol.
(x) The phenyl methyl
ether reacts with HI fo form phenol and
iodomethane and not
iodobenzene and methanol.
(xi) methanol is less
acidic than water.
(xii) alcohols can
act as weak base as well as weak acids.
(xiii) phenols do not
give protonation reaction readily.
(xiv) absolute
ethanol can not be obtained by factional distillation of ethanoland water
mixture.
6. Arrange the
following in the increasing order of property shown :
(i) methanol,
ethanol, diethylether, ethyleneglycol. (Boiling points)
(ii) phenol,
o-nitrophenol, m-nitrophenol, p-nitrophenol. (Acid strength)
(iii) dimethylether,
ethanol, phenol. (Solubility in water)
(iv) n-butanol,
2-methylpropan-1-ol, 2-methylpropan-2-ol. (Acid strength)
7. Give a chemical
test to distinguish between the following pair of compounds.
(i) n-propyl alcohol
and isopropylalcohol
(ii) methanol and
ethanol
(iii) cyclohexanol
and phenol.
(iv) propan-2-ol and
2-methylpropan-2-ol.
(v) phenol and
anisole
(vi) ethanol and
diethyl ether
8. An organic
compound (A) having molecular formula C3H7Cl on
reactionwith alcoholic solution of KCN gives compound B. The compound B onhydrolysis
with dilute HCl gives compound C. C on reduction withH2/ Ni gives
1-aminobutane. Identify A, B and C.
An optically active
compound having molecular formula C7H15Br
reactswith aqueous KOH to give C7H15OH, which
is optically inactive. Givemechanism for the reaction.A racemic mixture is
obtained which is optically inactive.
9. An organic
compound C8H9Br has
three isomers A, B and C. A is opticallyactive. Both A and B gave the white
precipitate when warmed with alcoholicAgNO3 solution
in alkaline medium. Benzoic acid, terephthalic and pbromobenzoicacid were
obtained on oxidation of A, B and C respectively.Identify A, B and C.
10. An alkyl halide X
having molecular formula C6H13Cl on
treatment withpotassium tert-butoxide gives two isomeric alkenes Y and Z but
alkene yis symetrical. Both alkenes on hydrogenation give 2, 3-dimethylbutane.
Identify X, Y and Z.
11.Give reasons for
the following :
(i) The bond length
of C–Cl bond is larger in haloalkanes than that inhaloarenes.
(ii) Although alkyl
halides are polar in nature but are not soluble inwater.
(iii) tert-butyl
bromide has lower boiling point than n-Butyl bromide.
(iv) haloalkanes
react with KCN to form alkyl cyanide as main productwhile with AgCN alkyl
isocyanide is the main product.
(v) sulphuric acid is
not used in the reaction of alcohol with Kl.
(vi) thionyl chloride
is the preferred reagent for converting ethanol tochloroethane.
(vii) haloalkanes
undergo nucleophilic substitution reaction easily buthaloarenes do not undergo
nucleophilic substitution under ordinaryconditions.
(viii) chlorobenzene
on reaction with fuming sulphuric acid gives orthoand para chlorosulphonic
acids.
(ix) 2, 4-dinitro
chlorobenzene is much more reactive than chlorobenzenetowards hydrolysis
reaction with NaOH.
(x) Grignard reagent
should be prepared under anhydrous conditions.
(xi) the dipole
moment of chlorobenzene is lower than that of cyclohexylchloride.
(xii) neopentyl
bromide undergoes nucleophilic substitution reactions veryslowly
(xiii) vinyl chloride
is unreactive in nucleophilic substitution reaction.
(xiv) An optically
inactive product isobtained after the hydrolysis ofoptically active 2-
bromobutane.
12.Arrange the
following in the increasing order of properly indicated :
(i) bromomethane,
chloromethane, dichloromethane. (Increasing order
of boiling points).
(ii) 1-chloropropane,
isopropyl chloride, 1-chlorobutane (Increasing order
of boiling point)
(iii)
dichloromethane, chloroform, carbon terachloride. (Increasing order
of dipole moment.
(iv) CH3F, CH3Cl, CH3Br, CH3l
(Increasing reactivity towards nucleophilic
substitution and
increasing order of dipole moment)
(v) o,m.p-dichlorobenzenes
(Increasing order of melting points).
13.Arrange the
following in the increasing order of properly indicated :
(i) bromomethane,
chloromethane, dichloromethane. (Increasing orderof boiling points).
(ii) 1-chloropropane,
isopropyl chloride, 1-chlorobutane (Increasing orderof boiling point)
(iii)
dichloromethane, chloroform, carbon terachloride. (Increasing orderof dipole moment.
(iv) CH3F, CH3Cl, CH3Br, CH3l
(Increasing reactivity towards nucleophilicsubstitution and increasing order of
dipole moment)
(v) o,m.p-dichlorobenzenes
(Increasing order of melting points).
14. How will you
bring about the following conversions?
(i) benzene to
3-bromonitrobenzene
(ii) ethanol to
but-1-yne
(iii) 1-bromopropane
to 2-bromopropane
(iv) benzene to
4-bromo-1-nitrobenzene
(v) aniline to
chlorobenzene
(vi)
2-methyl-1-propene to 2-chloro-2-methylpropane
(vii) ethyl chloride
to propanoic acid
(viii) but-1-ene to
n-butyl iodide
(ix) benzene to
phenylchloromethane.
(x) tert-butyl
bromide to isobutyl bromide.
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