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8/11/2019 DPPS___3__Atomic_Structure-1__03-6-14
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CAREER POINT
PRACTICE PROBLEM SHEET
PHYSICS
Topic Atomic Structure-3
Question based on Spectrum and spectrum lines
Q.1 If the series limit wavelength of the Lyman series for hydrogen atom is 912 , then the series limitwavelength for the Balmer series for the hydrogen atom is -
(1) 912 (2) 912 2 (3) 912 ()2
912
Q.2 In hydrogen s!e"tr#m, the shortest wavelength in Balmer series is $ %he shortest wavelength in Bra"&ett
series will 'e -
(1) 2 (2) (3) 9 () 1
Q.3 If the wave n#m'er of a s!e"tral line of Bra"&ett series of hydrogen is))
9times the *yd'erg "onstant$
+hat is the state from whi"h the transition has ta&en !la"e
(1) n (2) n . (3) n () n /
Q.4 0or the first mem'er of Balmer series of -s!e"tr#m, the wavelength is $ +hat is the wavelength of these"ond mem'er
(1) 3)
.
(2) 1(
3
(3) 9
() 2/
2
Q.5 If 1 and 2 are the wavelengths of the first mem'ers of the Lyman and as"hen series res!e"tively, then 12is 4(1) 13 (2) 13 (3) /. () /15
Q.6 6le"trons in a "ertain energy level n n 1, "an emit 3 s!e"tral lines$ +hen they are in another energy level,n n2$ %hey "an emit s!e"tral lines$ %he s!eed of the ele"trons in the two or'its are in the ratio4(1) 3 (2) 3 (3) 2 1 () 1 2
Q.7 0or an atom of ion having single ele"tron, the following wavelengths are o'served$ +hat is the val#e ofmissing wavelength, x
(1) 2 mm (2) mm (3) mm () 12 mm
Q.8 %he a""eleration of ele"tron in the first or'it of hydrogen atom is4
(1)3
2
h
m(2)
mr
h
2
2
(3)
322
2
rm
h
()
32
22
r
hm
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PRE
"PPS #$ - 0% 7is"#ssion on 3-6-214
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Q.! 8 !arti"le of mass m moves aro#nd in a "ir"#lar or'it in a "entro symmetri" !otential field ( )2
2Kr
ru = $
sing Bohr:s ;#anti
8/11/2019 DPPS___3__Atomic_Structure-1__03-6-14
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mmR
11912
19/5
===
912
2. ,2
=
22
21
111
nnR
0or shortest wavelength in Balmer series$
n1 2, n2
=
1
11R or
R
=
=
221
1
:
1R F ===
1:
RR
3.,2 1
*
9 *
22
14
1
n
4. ,4 1
*
223
14
2
13(
.R
:
1
*
22
1421
1(12R F
:
3(.R
R12
1(
5. ,4 0or Lyman series, n1 1 and n2 2 for firstline
3
1
1
1
2
1
1
1122
1
RRR =
=
=
0or as"hen series n1 3 and n2 for firstline
1
/
1
1
9
1
1
3
11
222
RRR =
=
=
15
/
/?1
3?
2
1 ==
R
R
6. ,1 =#m'er of emission s!e"tral lines
2
)1( =
nnN
2
)1(3 11
=
nn (in first
"ase)
or 121 =nn or (n14 3) (n1G 2)
%a&e !ositive root n1 3
8gain, 2
)1(
22 =
nn
(in se"ond "ase)
or 12222 = nn or (n24 ) (n2G 3)
%a&e !ositive root, or n2 =ow, velo"ity of ele"tron
nh
KZev
22=
3
1
2
1
1==
n
n
v
v
7. ,4 0rom *its "om'ination !rin"i!le
122313
111
nnnnnn +
=
Hr
11
1+=
x or x 12 mm
8. ,3
!. ,1r
mvKrru
dr
dF
2
)( ===
or mKrmv 2= and mvr 2nh
=2
2 nhmkrr or
2
1
=Km
nhr
and
mv2 Kr2
Km
nhK
%6 6 G 6
m
Knh
Km
nhK
Km
nhK
=
+
2221
1.,3 m$v$ c
E
=22 1
1
.
1$13E
2$1 1415J
v 52/
15
131/$1
11$2
=
mc
EF v $19
m?s
11.,1 1 red'#rg 13$ eK o, the energy needed to deta"h the ele"tron
is 13$ eK$%he energy in the gro#nd state
1 4 13$eK%he energy in first eA"ited state
2
1 4 13$ eK
5$
122=
= hc
3
12.,1 D i8 r
ev
2 r2 ef r2
13.,3 8!!ly "on"e!t of red#"ed mass
= emar F em2
2
ar =
14.,4 mto 'e re!la"ed 'y red#"ed mass s#"h that
mM
111+=
15.,3 0or "entre of mass at Oele"tron at Aand n#"le#satB, the !osition of "entre of mass OfromAis
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8/11/2019 DPPS___3__Atomic_Structure-1__03-6-14
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mM
Mr
mM
rMomr
+=
++
=1
16.,2 r3 r1 n2x 32 9x 2r n,
x
x
n
r
=
=
= 3922
CAREER POINT, CP Tower, IPIA, Road No.1, Kota (Raj.), Ph: 0744-3040000