B.Sc. General Examinations 2020
(Under CBCS Pattern)
Semester - I
Subject: CHEMISTRY
Paper : DSC 1A/2A/3A-T & DSC 1A/2A/3A-P (Atomic Structure & Organic Chemistry) Full Marks : 60 (Theory-40 + Practical-20)
Time : 3 Hours
Candidates are required to give their answers in their own words as far as practicable.
The figures in the margin indicate full marks.
Answer any two of the following questions : 2 × 20 = 40
1. (a) State Aufbau principle. 2
(b) What do you mean by dual properties of electron ? 2
(c) Show electronic arrangement of Cl and Fe2. 3
(d) Define lattice energy. 3
(e) Why hyper conjugation is known as no bond resonance ? 2 (f) Draw resonating structures of Anthracene indicating which are benzenoids and non
benzenoid structures. 3
(g) How acetylene is produced in oxy-acetylene flame process ? 2
Question Paper
VIDYASAGAR UNIVERSITY
(h) Give R&S nomenclature.
(i) OHC Br H NH2
(ii)
NMe2 H CHO
C H2 5 3
2. (a) (i) Ozonylysis of an olefin produce acetaldehyde and acetone-Propose it’s structure.
2 (ii) Hydrolysis of olefin is catalysed in presence of acid-explain. 2 (b) How a trans-olefin is produced by hydrogenation of alkyne (explain
mechanistically) ? 3
(c) State Born-Haber cycle. 3
(d) Define polarizing power and polarizability. 3
(e) Write structure of acetylene’s covalent bonding using VSEPR. 2 (f) Define dipole moment. Compare the dipole moment of the following compounds:
Cl Cl vs Cl
Cl ,
Me Me O
vs O 2+3
3. (a) pka value of acetic acid is 4.75 and formic acid is 3.75 — Explain the acidity
order. 3
(b) Phenol is more acidic than alcohol — Explain. 3
(c) How alkyne could be hydrogenated Cis - selectively by catalytic hydrogenation ? 3
(d) What is optical isomerism ? Give examples. 3
(e) What is Grignard reagent ? How is it prepared ? 3
(f) Explain the following reaction mechanically and express probable rate equation with appropriate naming ?
(i) Et Br H
CH3
HO (ii)
Br H
CH3
HO 5
4. (a) How does the atomic spectra of hydrogen revel the need for another atomic
structure model? 3
(b) State rule of filling of electrons in various electronic levels with spin multiplicity. 3 (c) State Born-Landé equation for calculation of lattice energy. 4 (d) What is homolytic and heterolytic cleavage ? Discuss the formation of carbocation,
carbanion and radical. 3
(e) Comment on Markownikoff and anti-Markownikoff addition of HBr to an oliefin.
5 (f) Write the preparation of alkane by Wurtz reaction and preparation of alkyne by
dehydrohalogenation of vicinaldihalide ? 2
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öë ö„þy˜ ”%!Ýþþ ²ÌöìÙÀîû vþz_îû ”yç S20 × 2 = 40V
1Ð S„þV xyvþzšþîyvþz ˜#!“þ!Ýþîû ¢‚Kþy öœ…Ð 2
S…V £zö위þÝþÆöì˜îû ÷m“þ ÷î!ŸÜTÄ îœöì“þ „þ# öîyGþÚ 2
S†V CI ~î‚ Fe2 ~îû £zö위þÝþÆöì˜îû !î˜Äy¢ ö”…yç Ú 3
S‡V Latice Ÿ!_« !˜•Åyîû’ „þîûÐ 3
SˆV £y£zþ™yîû„þ˜‹%ö솟˜ ö„þ îõþ˜£#˜ ¢‚ßþ™¨˜ îœy £ëû ö„þ˜Ú 2
S‰þV xÄy˜öìíÊ¢öì˜îû ¢‚ßþ™¨˜ „þyàþyöì›y öœ… ~î‚ öî!O˜öìëûvþ ç ˜˜éôéöî!O˜öìëûvþ „þyàþyöì›y ö”…yçÐ 3 SŠéV „þ#¦þyöìî xÄy!¢!Ýþ!œ˜ x!:xÄy!¢!Ýþ!œ˜ !Ÿ…y ²Ì!e«ëûy ÷“þ!îû „þîûy £ëûÚ 2
S‹V !˜Á¬!œ!…“þ öëï†=!œîû R ~î‚ S ˜y›„þîû’ ”yçÐ 3
(i) OHC Br H NH2
(ii)
NMe2 H CHO C H2 5
2Ð S„þV (i) ~„þ!Ýþ x¢Á™,_« ÷‹î öëïöì†îû 狘 !˜!¢¢ „þöìîû xÄy!¢Ýþyœ!vþ£y£zvþ ç ~!¢öìÝþy˜ þ™yçëûy
“þyîû „þyàþyöì›yîû ²Ìhßþyî ”yçÐ 2
(ii) xÄyœ!šþöì˜îû £y£zöìvÈþyœy£z!¢¢ xÄy!¢öìvþîû x˜%‡Ýþ„þ vþzþ™!ßþi!“þöì“þ “þîûy!§º“þ £ëûÚ 2 S…V xÄyœ!„þöì˜îû £y£zöìvÈþyöì‹ö옟˜ myîûy ÝþÆyªéôéçœ!šþ˜ „þ#¦þyöìî vþzêþ™y!”“þ £ëûÚ S!î!e«ëûyöì„þ îÄy…Äy
„þîûV 3
S†V Born-Haber ‰þe«!Ýþ !œ…Ð 3
S‡V ö›îû&„þîû’ (Polarizing) Ÿ!_« ~î‚ ö›îû&„þîû’ öëy†Ä“þy (Polarizability) ¢‚Kþy !œ…Ð 3 SˆV VESPR îÄî£yîû „þöìîû xÄy!¢!Ýþ!œöì˜îû ¢›îyëû îõþöì˜îû „þyàþyöì›y !œ…Ð 2 S‰þV !möì›îû&¼y›„þ!Ýþîû ¢‚Kþy !œ…Ð
!˜Á¬!œ!…“þ öëï†=!œîû !möì›îû&¼y›„þ “%þœ˜y „þîû&˜
Cl Cl vs Cl
Cl
Me Me O
vs O 2+3
3Ð S„þV ~!¢!Ýþ„þ xÄy!¢öìvþîû pka ›y˜ 4.75 ~î‚ šþ!›Å„þ xÄy!¢vþ pka 3.75 xÄy!¢vþ!Ýþîû e«› îÄy…Äy
„þîûÐ 3
S…V öšþ˜œ xÄyœöì„þy£öìœîû ö‰þöìëû öî!Ÿ xy!ÁÔ„þ îÄy…Äy „þîûÐ 3
S†V „þ#¦þyöìî xÄyœ!„þ˜öì„þ x˜%‡Ýþ„þ £y£zöìvÈþyöì‹ö옟öì˜îû ›y•Äöì› Cls-¢›yîëûî îyŠéy£z „þöìîû
£y£zöìvÈþy!‹öì˜Ýþ „þîûy öëöì“þ þ™yöìîûÚ 3
S‡V xþ™!Ýþ„þÄyœ xy£zöì¢y›!îû‹› „þ#Ú vþz”y£îû’¢£ îÄy…Äy „þîûÐ 3
SˆV Grignard !î„þyîû„þ!Ýþ !„þÚ £z£y !„þ¦þyöìî ²Ìlßþ“þ „þîûy £ëûÚ 3 S‰þV !˜öìÁ¬y_« ²Ì!“þ!e«ëûy!Ýþ ëy!sþf„þ¦þyöìî ëíyëí ˜y›„þîûöì’îû ¢yöìí ¢½þyîÄ £yîû ¢›#„þîû’!Ýþ îÄy…Äy
„þîû&˜Ú
(i) Et Br H CH3
HO (ii)
Br H
CH3
HO 5
4Ð S„þV £y£zöìvÈþyöì‹öì˜îû þ™yîû›y’!î„þ î’Åyœ# „þ#¦þyöìî vþzþ™ë%_« þ™yîû›y’!î„þ „þyàþyöì›yîû ›öìvþœ!Ýþîû
²Ìöìëûy‹˜#ëû“þy ö”…yëûÚ 3
S…V !î!¦þ§¬ £zö위þÝþÆöì˜îû „þöìÇþ £zö위þÝþÆöì˜îû !î˜Äy¢ !ßþ™öì˜îû x!¦þ›%… ¢£ !œ…Ú 3 S†V Born-Landè ¢›#„þîûöì’îû ¢y£yëÄ Latice Ÿ!_«îû †’˜y „þîûÐ 4 S‡V ö£yöì›yöìœ!Ýþ„þ ~î‚ !£Ýþyöìîûy!œ!Ýþ„þ !î¦þy‹˜ „þ#Ú „þy„þyöìîÅy„þÄÝþyëû˜– „þyîÅy˜yëû˜ ~î‚ ›%_« ›)œ„þ
†àþ˜ ²Ì!e«ëûy !œ…Ð 3
SˆV HBr ~îû ›y„Åþyvþz˜„þšþ ~î‚ xÄy!rÝþéôé›y„Åþyvþz˜„þšþ ¢‚öìëy‹˜ îÄy…Äy „þîûÐ 5 S‰þV Wurtz ²Ì!“þ!e«ëûy myîûy xÄyœöì„þöì˜îû ²Ìlßþ!“þ ~î‚ ¦þÄ!¢˜yœéôévþy£z£Äœy£zöìvþîû (Vaccinaldihalide)
!vþ£y£zöìvÈþyöì‹ö옟˜ myîûy xÄyœ„þy£zöì˜îû ²Ìlßþ!“þ !œ…Ð 2
Paper - DSC 1A-P (Practical) Full Marks : 20
Answer any one of the following questions : 1 × 20 = 20
1. Write the principle and experimental methods for estimation of sodium carbonate and sodium hydrogen carbonate present in a mixture.
2. Write a note on iodometric estimation of Cu (II) ions.
3. Discuss about the detection of special elements (N, S, Cl, Br, I) present in an organic compound.
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!˜Á¬!œ!…“þ þ™îû#Çþyîû öë ö„þy˜ ~„þ!Ýþ ¢Á™y”˜ „þîû&˜Ð Sþ™îû#Çþyîû !”˜ œÝþy!îû myîûy !˜öì”Å!Ÿ“þ £öìîV
!˜!”ÅÜT þ™îû#Çþyîû ›y˜ !î¡ìöìëû !¢kþyhsþ ö˜öìî˜ þ™îû#Çþ„þÐ
1Ð ~„þ!Ýþ !›×öì’ vþzþ™!ßþi“þ ö¢y!vþëûy› „þyîÅöì˜Ýþ ~î‚ ö¢y!vþëûy› £y£zöìvÈþyö싘 „þyîÅöì˜öìÝþîû ›yey !˜’Åëû „þîûÐ 2Ð Cu(II)éôéxyëû˜ ~îû xyöìëûyöìvþyöì›!ÝþÆ„þ ~!ÞÝþö웟˜ ~îû çþ™îû ö˜yÝþ öœ…Ð
3Ð ²Ì”_ ÷‹î öëï†=!œöì“þ vþzþ™y”y˜ (N, S, Cl, Br, I) ¢˜y_« „þîûÐ
