O CHE-1 : ATOMS AND MOLECULES

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1 CHE-1 I BACHELOR OF SCIENCE (B.Sc.) O Term-End Examination December, CHEMISTRY. O CHE-1 : ATOMS AND MOLECULES Time : 1 hour Maximum Marks : 25 Note : Answer all the five questions. Instructions : CHE-1 : ATOMS AND MOLECULES AND CHE-2 : INORGANIC CHEMISTRY Students registered for both CHE-1 & CHE-2 courses should answer both the question papers in two separate answer books entering their enrolment number, course code and course title clearly on both the answer books. Students who have registered for CHE-1 or CHE-2 should answer the relevant question paper after entering their enrolment number, course code and course title on the answer book. CHE-1 1 P.T.O.

2 CHE-1 : ATOMS AND MOLECULES Use the following data wherever required : Planck's constant h-= X Js Velocity of light c= 2.98 X 108 ms 1 Mass of electron, me = x kg Charge on electron e,= x 10-19C Permittivity of free space, e o = x c2-1 m-2 1. Answer any two of the following : Write the electronic configuration of Fe atom (Atomic number = 26). Complete the following nuclear reaction Th ---> 88 Ra +? (c) Give the type of hybridisation of the central atom of IF5. 2. Answer any two of the following : Explain the significance of 45 and 42. Predict the coordination number of potassium ion in KBr crystal (Radii of K± and Br are 133 pm and 195 pm respectively). (c) Predict the magnetic moment of Mn 2+ ion in 11B Unit (Atomic number of Mn is 25). CHE-1 2

3 3. Answer any two of the following : 6 Write the molecular orbital configuration of B2 and Q2. Calculate their bond orders. Calculate the force constant of hydrochloric acid, if this compound absorbs at 2894 cm -1 and its reduced mass is x kg. (c) Illustrate the difference between isotopes, isobars and istones with suitable examples. 4. Answer any two of the following : 8 What is photoelectric effect? Give its mathematical form. Calculate the wavelength of the light required to eject a photoelectron from caesium metal with a kinetic energy of 2.0 x J (,)0 for caesium is 4.55 x Hz). Explain why are the carbon-oxygen bond - lengths in CO 2 3 ion equal? (c) (i) The Ionisation energy of nitrogen is 1403 k J mol -1 but for oxygen it is 1314 k J mol -1. Explain. (ii) Which of the two molecules is polar BF3 or NH3? Why? CHE-1 3 P.T.O.

4 5. Answer any one of the following : 5 Drive an expression relating radius of the atom to the mass, charge and orbit number of a hydrogen like atom. What is the energy value of an electron if n = co? The bond length of 1H80Br molecule is 141 pm. Calculate the wave number in cm-1 for the following rotational transition; J=1 >J 1 = 2. - o 0 o - CHE-1 4

5 -fft.7w1.- 1 f'd7t9' tai ic-ict) (4'.74:17ft.) ti 71 Id TRI1TT fqiil-cit, 2009,t4ii 11?IFR Tft:CM1.-1 : LutHt ua aft H AN :1 bp/di 37fg/W W 25 9t-e: 779frrirwmql. k dth : : urinal aft awl aft T11.7W.t.-2 : ar*t-419 (i) EPP' 7t7V.e q t-2 q)-tiriver-*--4 ren r/v-ff g, Y dri< 37MT dru yfti7wt3t7#3tri37 3/T*7* ti1 4a5H U27T (in e T17 Lti ch- qi ch C'Rgch(.e.-1 TIT?:17.7W.e.-2 f kw, v# svi? so,v01 dr/t dr/?-- 37TR7 ttnelv 0)5 UETT (.1W/47 41 TR' w(h-hi ch I CHE-1 5 P.T.O.

6 *79%1. -1 : AT /cWeichrt/ 3/7/7 fv-ircirtgri aliwtywri ei/j/ TrT F-NclI ch it= x J s M ohlkf C = 2.98 x 108 ms -1.TT oe , Me = x kg 3-Tft, e= x 10-19C ftqfff 4 ratrilodi, E0 = x c2n-1 m F-14-Irriroct 4.# fwtt 77-4 t &TR : Fe TR-149 fd-4:1tfl (IRT19 4(9?-11=26) I Ci (Acr 3451-f-*-7T f : 232 Th 228 Ra +? (c) IF5it 41113j t 4911,01...T.51-*-17 qlrzi 2. F-14-1FoRgo 4 A. fwt 74t drit : qi t112.w1- Trrzt--*---dr k-1 1-IIIW I KBr il LO.Ni q H T1 d t-i4441,s11 4(9?-11.WE 7111-i (K + *Br altztt k1: 133 pm pm t) I (c) Mn TrEriµB ( Mn rch TRI49 4(seif 25 t) I CHE-1 6

7 3. F-P---irriliAci.# fwt '41-979)' drit rs3-r : 6 B2 3th Q2 t 311:1 fd-riff ffffti71 3Tr4tT A7 41 I #2.T yrct oi cm 1 tr{3 13T cw4j t 2TT W-*1 W11-11d c,44-11-f x10-27 kg t (C) 1f9-T, 1114 Tf17 clict 3tT -TaTTR I 4. r-p-iirirod -(4 fw l't Nk-if d'cr : 8 U chlkt 51-Td ITT t? -P:fk Fti TR I ti,3114 Nig -4 -# 2.0 X J4Irckl Pichic14 chki N chri t aird-ttwm i141? W"-T..if77 I ( fwr.k= 4.55 x 1014 Hz f) CO3 2 aiff wr4ff-3-ti- 3TT Tff (c) (1) 111q1\m1 3-Trzm. d) Tii 1403 k J mol-1 t 7-4ft" aff k J mol t. I (ii) BF3 zit NH3 Off xtzi t? crql? CHE-1 7 P.T.O.

8 5. F-H-ircirci 14 A f-*-th- crt 37It I 5.),1.-1 ch1 f(97 TcF til-nchtui 31-rkw 3 t 4t.V-1 I -A -4-4N-u 4).& qzfl n= ti 1 H80Br 39 31T4q141 tn-4' 413.& t I F (Ncf Th. 4t9,-41 ch-1 cm- 1 ituv r j=1j1=2. - o 0 o - CHE-1 8

BACHELOR OF SCIENCE (B.Sc.) Term-End Examination June, B.Sc. EXAMINATION CHE-1 : ATOMS AND MOLECULES AND CHE-2 : INORGANIC CHEMISTRY

No. of Printed Pages : 15 00881 CHE-1 BACHELOR OF SCIENCE (B.Sc.) Term-End Examination June, 2010 CHEMISTRY CHE-1 : ATOMS AND MOLECULES Time : 1 hour Maximum Marks : 25 B.Sc. EXAMINATION Instructions :