Download SGBAU (Sant Gadge Baba Amravati university) BSc 2019 Summer (Bachelor of Science) 6th Sem Chemistry Previous Question Paper
B.Sc. Part-III (Semester?VI) Examination
CHEMISTRY
Time : Three Hours] [Maximum Marks : 80
Note :?(1) ALL questions are compulsory,
(2) Question No. l carries 8 marks while each of the remaining SIX questions
carries 12 marks.
(3) Draw diagrams and write equations wherever necessary.
(4) Use of scienti?c calculators is allowed.
1. (A) Fill in the blanks :
(i) According to quantum theory, the radiations consist of packets of energy
called __
(ii) The range of ?nger print region is
(iii) The elements which are absolutely necessary for life process in a very small
amount are called as
(iv) The complexes showing reaction within one minute, 1 M concentration and at
room temperature are called as complexes. 2
(B) Choose the correct alternative :
(i) The intermediate formed in SN2 mechanism showsr geometry.
(a) Pcntagonal (b) Trigonal
(c) Octahedral (d) Pentagonal bipyramidal
(ii) Expression for energy of a particle in one dimensional box is :
() "2"2 (b) ??2
a
8ma2 2sz2
() nzh2 (d) nzh
c _
4ma2 Zma?
(iii) Number of NMR signals in propane is :
(a) Four (b) Threc
(c) Two (d) One
(iv) Geometrical shape of Cr(CO)6 molecule is :
(:1) Linear (b) Octahcdral
(c) Tetrahedral (d) Pentagonal bipywamidal 2
YBC?l 5332 I (C0ntd.)
(C) Answer in ONE sentence : 4
(i) De?ne the term auxoehmme.
(ii) What are phosphonitriiic polymers 2?
(iii) What is Compton effect ?
(iv) What is potentiomctrit titration ?7
UNI'I?~?l
2 (21) Describe the procedure of colourimctric determination 0.? concentration of Cu"
ions. 4
(b) Explain SN'-dissociative mechanism of substitution in octahedral complexes. 4
(c) Describe the process of descending chromatography. 4
OR
3. (p) What is Bccr-Lamberl?s law ?.7 Write its mechanical expresson and limitations. 4
(q?) Define labile and inert complexes with an example of each. 4
(r) What is paper chromatography '2 Write its applications.
UNIT?ll
4. (9.) Explain the structure nt? Fc- (CO)S molecule on the basis of valence bond theory. 4
(b) How is phosphonitrilit? chloride prepared from I?Cli and NH4(31 ? Give its reaction with
ammonia. 4
(c) Explain the role 01? K' in biological activities. 4
OR
5 (p) What is the action of follouing on NHCO)? : (i) Halogen and (ii) H2804 2? 4
(q) What happens when tPNClyb1 reacts with :
(i) Alcohol
(ii) (IOHG '2 4
(r) Discuss the role 01? C212? in metabolic activity. 4
UNIT?III
6 (:1) Calculate the vibrational degrees 01? freedom for the foilowing molecules in IR
spectroscopy :
(i) (30:
(ii) NH3
(iii) Benzene
(iv) CH?. 4
(b) Explain the following: electronic transitions with suitable example :
(i) 1t ?> TN 2
(ii) 11 ?> 0* Transition. 2
(c) Explain the following; terms with diagram :
(i) Scissoring
(ii) Twisting. 4
OR
YBC?IS332 3
(Contd.)
7. (P)
(q)
(r)
(b)
(e)
9- (p)
(q)
(0
Explain the following terms 2
(i) Hypsochromic shift
(ii) Hyperchromic effect.
Differentiate the following pairs of compounds on the basis of IR spectroscopy :
(i) acetamide and acetic acid
(ii) acetone and ethanol.
4
What types of electronic transitions do you expect in each of the following compounds ?
(i) CH4
(ii) CH2 = CH2
(iii) CHJ-Cl
(iv) CH3?H = O
UNIT?[V
How will you distinguish following pairs by their NMR spectra ?
(i) CH3COCH3 and CHJCHO
(ii) CHJOCH3 and CIIJCIIZ-OII
Calculate m/z value of each of the following in Mass Spectroscopy :
(i) [(CHJLCHJ?
(ii) [CHs?NHJ
Explain the following terms with an example :
(i) Spin-spin coupling
(ii) Chemical shift.
0R
Explain in brief the principle of mass spectroscopy.
Write the NMR signals shown by following compounds :
(i) Ethyl bromide
(ii) 1, 3-dichloropropane
(iii) Ethyl acetate
(iv) Isopropyl bromide.
Calculate m/z values for each of the following molecular ions :
(i) [CoHs?CHsr
(ii) [CHs?CHZ?OH]?
YBC?15332 3
(Contd.)
10. (a)
(b)
(e)
11. (p)
(q)
12. (a)
(b)
(C)
13- (p)
(q)
(r)
UNIT?V
Derive an expression for the energy of a free particle in on: dimensional box. 4
What do you understand by dual character of matter ?? 4
The work function of Cs metal is 2.14 eV. Calculate the kin :tic energy and the speed
of the electrons emitted when the metal is irradiated with light of wavelength
700 nm. 4
OR
What is the physical signi?cance of w and w2 ? 4
What is threshold frequency ?? How is this frequency related to the work function ??
4
An electron is con?ned in one dimensional box of width 4.0 x 10'?1 m. Calculate its
energy in the fourth energ} level. 4
UNIT?VI
De?ne :
(i) pKa of the weak acid
(ii) Concentration cell
(iii) Q-value
(iv) Nuclear fusion reactions. 4
How pH of the solution is determined using the hydrogen gas electrode ?
Explain the nuclear force on the basis of meson theory. 4
0R
Give any four evidences in favour of Magic numbers.
Derive an equation for EMF of concentration cell without transference.
(i) Give any two applicatxons of radioisotopes in industry.
(ii) Give any two adx antages of glass electrode. 4
YBC- ~l 5332 4 525
This post was last modified on 10 February 2020