IISER Chemistry - Purification And Characteristics of Organic Compounds
Exam Duration: 45 Mins Total Questions : 30
The elements of nitrogen and ulphur are present in an organic compound.which of the sodium compounds(is/are)present in the sodium extract on fusing it with sodium?
- (a)
thicocyante
- (b)
cyanide and sulphide
- (c)
sulphite and cyanide
- (d)
nitrate and cyanide
The volume of co2 evoled on complete combustion of 1 mole of ethylene in excess oxygen in litres is
- (a)
22.4
- (b)
44.8
- (c)
2.24
- (d)
NONE OF THESE
An organic compound is found to contain C=39.9%,H=6.7%,O=53.4%. Its empirical formula is
- (a)
CHO
- (b)
CHO2
- (c)
CH2O2
- (d)
CH2O
Which of the following is blood red compound in quantitative estimation of nitrogen and sulphur together?
- (a)
Fe4[Fe(CN)6]3
- (b)
Fe(SCN)3
- (c)
FeSCN
- (d)
NA2S,NACN
Two solids Which are soluble in same to different extent may be seperated by
- (a)
crystllisation
- (b)
evaporation
- (c)
fractional crystallisation
- (d)
sublimation
Fractional crystalliation is carried out to seperate a mixture such as
- (a)
organic solids mixed in inorganic solide
- (b)
organic solids highly soluble in water
- (c)
organic solids having small difference in their solubilities in suitable solvant
- (d)
organic solids having great difference in their solubilities in suitable solvents
The empirical formula of a compound is CH2, 1 mole of the compound has mass 14 g.its moleculer formula is
- (a)
CH2
- (b)
C2H4
- (c)
C3H8
- (d)
C3H6
A compound has 40% carbon and 6.66% hydrogen.Its empitical formula is
- (a)
CH2
- (b)
CH2O
- (c)
C2H5O
- (d)
CH2O2
A mixture of NACL and KCL in solution can be seperated by
- (a)
evaporation
- (b)
distillation
- (c)
fractional distillation
- (d)
fractional crystallisation
in a Carius estimation 0.189 g of an organic chloro compound gave 0.287 g of AgCL precipitate.The approximate percentage of choline in the compound
- (a)
30
- (b)
32
- (c)
34
- (d)
38
An organic compound contains 8 percent ozygen.its minimum moleculer weight would be
- (a)
100
- (b)
200
- (c)
300
- (d)
400
Chlorine in organic compound is estimated by
- (a)
Kjeldahl's method
- (b)
Carius method
- (c)
Direct argentiometry
- (d)
High pressure liquid chromatography
Which one of the following is not used for the purification of solid impurities
- (a)
Distillation
- (b)
sublimation
- (c)
Crystallisation
- (d)
NONE OF THESE
Absolute alcohol is prepared by
- (a)
Fractional distillation
- (b)
Kolbe's method
- (c)
Vacum distillation
- (d)
Azeotropic distillation
A mixture contains four solid organic compounds A,B,C and D.on heating only C changes from solid to vapour state.C can be seperated from the rest in the mixture by
- (a)
distillation
- (b)
sublimation
- (c)
fractional distillation
- (d)
crystallisation
A dibasic acid containing C,H and O Was found to contain C = 26.7% and H = 2.2%. The vapour density of diethyl ester was found to be 73. What is moleculer formula of acid?
- (a)
CH2O2
- (b)
C2H2O4
- (c)
C3H3O4
- (d)
C4H4O4
In Lassaigne's test for nitrogen,the blue colour is due to the formation of
- (a)
Potassium ferrocyanide
- (b)
Sodium cyanide
- (c)
Sodium ferrocyanide
- (d)
Ferri-ferrocyanide
Which of the following techniques is most suitable for purification of cyclohexanone from a mixture containing benzonic acid, isoamylalcohol, cyclohexane and cyclohexanone?
- (a)
Crystallisation
- (b)
IR spectroscopy
- (c)
Sublimation
- (d)
Gas chromarography
The sinplest formula of a compound containing 50% of element X (at. wt. 10) and 50% of element Y (at. Wt. 10) is
- (a)
XY
- (b)
XY2
- (c)
X2Y
- (d)
X2Y32
There is no direct test for the detection of following in organic compound :
- (a)
CI
- (b)
N
- (c)
S
- (d)
O
The most satisfactory method to separate is to use
- (a)
Fractional crystallisation
- (b)
Sublimation
- (c)
Chromatography
- (d)
Benedict's reagent
Amongst the following statements, the statement which is not applicable to Beilstein's test is
- (a)
greenish or blue green flame is due to the formation of cupric halides.
- (b)
this test is a very sensitive test and can be easily performed.
- (c)
this test confirms the presence of halogen atom
- (d)
this test does not tell us which halogen atom is present in the organic compound.
Compounds like urea, thiourea also produces greenish or blue green colour when heated with copper wire. Therefore this test does not confirms the presence of halogen atom in the compound.
If 0.1g of an organic compound containing phosphorus produces 0.222g of Mg2P2O7, the percentage of phosphorus present in the compound is
- (a)
31
- (b)
0.2
- (c)
66
- (d)
62
The percentage of O present in the organic compound is given by
% of P=\(\frac { 62 }{ 222 } \times \frac { wt.of\quad Mg_{ 2 }{ P }_{ 2 }{ O }_{ 7 } }{ wt.of\quad organic\quad compound } \times 100\)
=\(\frac { 62 }{ 222 } \times \frac { 0.222 }{ 0.1 } \) x 100=62%
The silver salt of a monobasic acid on heating produces 60% of silver. The weight of the acid is
- (a)
37
- (b)
57
- (c)
88
- (d)
73
Eq. weight of silver salt = Eq.weight of Ag \(\Rightarrow{100\over E}={60\over108}\)
Equivalent weight of the silver salt of an acid, \(E=108X{100\over 60}=180\)
Equivalent weight of an acid =E-108+1=180-108+1=73
The fragnance of flowers is due to the presence of some steam volatile organic compounds called essential oils. These are generally insoluble in water at room temperature but are miscible with water vapour in vapour phase. A suitable method for the extraction of these oils from the flowers is
- (a)
distillation
- (b)
crystallisation
- (c)
distillation under reduced pressure
- (d)
steam distillation
Oils are extracted by steam distillation
Air contains 20% O2 by volume. The volume of air that will be required for 100cc of acetylene is
- (a)
1250cc
- (b)
1064cc
- (c)
212.8 cc
- (d)
500 cc
The combustion of acetylene is represented as
2C2H2+5O2 ⟶4CO2+2H2O
2 cc 5 cc
100 cc 25 cc
The volume of air that would be required for 100 cc of acetylene is 100/250=1250 cc.
In the Lassaigne's test for nitrogen in an organic compound, the Prussian blue colour is obtained due to the formation of
- (a)
Na4[Fe(CN)6]
- (b)
Fe4[Fe(CN)6]3
- (c)
Fe2[Fe(CN)6]
- (d)
Fe3[Fe(CN)6]4
The Prussian blue coloured compound is Fe4[Fe(CN)6]3
The compound ClCH2COOH was heated with fuming HNO3 and AgNO3 in a Carius tube. A white precipitate is formed after filteration and washing of the reaction mixture. The white precipitate formed is
- (a)
Ag2SO4
- (b)
AgNO3
- (c)
ClCH2COOAg
- (d)
AgCl
AgCl is formed during the estimation of chlorine.
4% of sulphur is present alongwith carbon and hydrogen in an organic compound. The minimum molecular weight of the compound is
- (a)
100
- (b)
400
- (c)
500
- (d)
800
For the minimum molecular weight of the compound, the compound must contains one 5-atom. The percentage of sulphur is given by
S%=\(\frac { Weight\quad of\quad one\quad S-atom }{ Minimum\quad moleclar\quad wt } \times 100\)
4=\(\frac { 32 }{ Minimum\quad molecular\quad weight } \times 100\)
Minimum molecular weight=\(\frac { 32\times 80 }{ 4 } \)=800
The compound formed in the positive test for nitrogen with the Lassaigne solution of an organic compound is
- (a)
Fe(CN)3
- (b)
Fe4[Fe(CN)6]3
- (c)
Na4[Fe(CN)5NOS]
- (d)
Na3[Fe(CN)6]
If nitrogen is present in organic compound, then sodium extract contains Na4[Fe(CN)6]
Na+C+N \(\overset { Fuse }{ \longrightarrow } \) NaCN
FeSO4+6NaCN ⟶Na4[Fe(CN)6]+Na2SO4
(A)
(A) when reacts with FeCl3, it changes to Prussian blue coloured compound, Fe[Fe(CN)6]3
4FeCl3+3Na4[Fe(CN)6] ⟶ Fe4[Fe(CN)6]3+12NaCl