
If in nature there may not be an element for which the principal quantum number n > 4, then the total possible number of elements will be
A)
60 done
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B)
32 done
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C)
4 done
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D)
64 done
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The ionisation potential of hydrogen atom is 13.6 volt. The energy required to remove an electron in the n = 2 state of the hydrogen atom is
A)
27.2 eV done
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B)
13.6eV done
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C)
6.8eV done
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D)
3.4eV done
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An electron makes a transition from orbit n = 4 to the orbit n = 2 of a hydrogen atom. The wave number of the emitted radiations (R = Rydberg's constant) will be
A)
\[\frac{16}{3R}\] done
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B)
\[\frac{2R}{16}\] done
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C)
\[\frac{3R}{16}\] done
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D)
\[\frac{4R}{16}\] done
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According to Bohr's model, the radius of the second orbit of helium atom is
A)
0.53 \[\overset{\text{o}}{\mathop{\text{A}}}\,\] done
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B)
1.06 \[\overset{\text{o}}{\mathop{\text{A}}}\,\] done
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C)
2.12 \[\overset{\text{o}}{\mathop{\text{A}}}\,\] done
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D)
0.265 \[\overset{\text{o}}{\mathop{\text{A}}}\,\] done
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Hydrogen atoms are excited from ground state of the principal quantum number 4. Then the number of spectral lines observed will be
A)
3 done
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B)
6 done
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C)
5 done
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D)
2 done
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Which of the following statements are true regarding Bohr's model of hydrogen atom 
(I) Orbiting speed of electron decreases as it shifts to discrete orbits away from the nucleus 
(II) Radii of allowed orbits of electron are proportional to the principal quantum number 
(III) Frequency with which electrons orbits around the nucleus in discrete orbits is inversely proportional to the principal quantum number 
(IV) Binding force with which the electron is bound to the nucleus increases as it shifts to outer orbits 
Select correct answer using the codes given below 
Codes : 
A)
I and III done
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B)
II and IV done
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C)
I, II and III done
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D)
II, III and IV done
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What will be the angular momentum of a electron, if energy of this electron in Hatom is 1.5eV (in Jsec)
A)
\[1.05\times {{10}^{34}}\] done
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B)
\[2.1\times {{10}^{34}}\] done
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C)
\[3.15\times {{10}^{34}}\] done
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D)
\[2.1\times {{10}^{34}}\] done
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The energy of hydrogen atom in its ground state is  13.6 eV. The energy of the level corresponding to the quantum number n is equal 5 is
A)
 5.40 eV done
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B)
 2.72 eV done
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C)
 0.85 eV done
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D)
 0.54 eV done
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Energy of an electron in an excited hydrogen atom is  3.4 eV. Its angular momentum will be: \[h=6.626\times {{10}^{34}}Js\]
A)
\[1.11\times {{10}^{34}}J\ \sec \] done
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B)
\[1.51\times {{10}^{31}}J\ \sec \] done
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C)
\[2.11\times {{10}^{34}}J\ \sec \] done
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D)
\[3.72\times {{10}^{34}}J\ \sec \] done
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Which state of triply ionised Baryllium \[(B{{e}^{+++}})\] has the same orbital radius as that of the ground state of hydrogen
A)
n = 4 done
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B)
n = 3 done
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C)
n = 2 done
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D)
n = 1 done
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As the electron in Bohr orbit of Hydrogen atom passes from state \[n=2\] to \[n=1\], the kinetic energy K and potential energy U change as
A)
K twofold, U fourfold done
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B)
K fourfold, U twofold done
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C)
K fourfold, U also fourfold done
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D)
K twofold, U also twofold done
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Radius of first Bohr orbit is r. What is the radius of 2nd Bohr orbit?
A)
8 done
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B)
2r done
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C)
4r done
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D)
\[2\sqrt{2r}\] done
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In the above figure D and E respectively represent
A)
Absorption line of Balmer series and the ionization potential of hydrogen done
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B)
Absorption line of Balmer series and the wavelength lesser than lowest of the Lyman series done
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C)
Spectral line of Balmer series and the maximum wavelength of Lyman series done
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D)
Spectral line of Lyman series and the absorption of greater wavelength of limiting value of Paschen series done
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Every series of hydrogen spectrum has an upper and lower limit in wavelength. The spectral series which has an upper limit of wavelength equal to 18752 \[\overset{\text{o}}{\mathop{\text{A}}}\,\] is
A)
Balmer series done
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B)
Lyman series done
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C)
Paschen series done
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D)
Pfund series done
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According to Bohr's theory the radius of electron in an orbit described by principal quantum number n and atomic number Z is proportional to
A)
\[{{Z}^{2}}{{n}^{2}}\] done
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B)
\[\frac{{{Z}^{2}}}{{{n}^{2}}}\] done
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C)
\[\frac{{{Z}^{2}}}{n}\] done
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D)
\[\frac{{{n}^{2}}}{Z}\] done
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A hydrogen atom (ionisation potential 13.6 eV) makes a transition from third excited state to first excited state. The energy of the photon emitted in the process is
A)
1.89 eV done
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B)
2.55 eV done
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C)
12.09 eV done
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D)
12.75 eV done
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Which of the following statements about the Bohr model of the hydrogen atom is false
A)
Acceleration of electron in n = 2 orbit is less than that in n = 1 orbit done
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B)
Angular momentum of electron in n = 2 orbit is more than that in n = 1 orbit done
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C)
Kinetic energy of electron in n = 2 orbit is less than that in n = 1 orbit done
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D)
Potential energy of electron in n = 2 orbit is less than that in n = 1 orbit done
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The Rydberg constant R for hydrogen is
A)
\[R=\left( \frac{1}{4\pi {{\varepsilon }_{0}}} \right).\frac{2{{\pi }^{2}}m{{e}^{2}}}{c{{h}^{2}}}\] done
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B)
\[R=\left( \frac{1}{4\pi {{\varepsilon }_{0}}} \right).\frac{2{{\pi }^{2}}m{{e}^{4}}}{c{{h}^{2}}}\] done
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C)
\[R={{\left( \frac{1}{4\pi {{\varepsilon }_{0}}} \right)}^{2}}.\frac{2{{\pi }^{2}}m{{e}^{4}}}{{{c}^{2}}{{h}^{2}}}\] done
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D)
\[R={{\left( \frac{1}{4\pi {{\varepsilon }_{0}}} \right)}^{2}}.\frac{2{{\pi }^{2}}m{{e}^{4}}}{c{{h}^{3}}}\] done
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The third line of Balmer series of an ion equivalent to hydrogen atom has wavelength of 108.5 nm. The ground state energy of an electron of this ion will be
A)
3.4 eV done
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B)
13.6 eV done
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C)
54.4 eV done
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D)
122.4 eV done
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Hydrogen atom excites energy level from fundamental state to n = 3. Number of spectrum lines according to Bohr, is
A)
4 done
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B)
3 done
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C)
1 done
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D)
2 done
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When an electron in hydrogen atom is excited, from its 4th to 5th stationary orbit, the change in angular momentum of electron is (Plancks constant: \[h=6.6\times {{10}^{34}}J\text{s}\]
A)
\[4.16\times {{10}^{34}}\,J\text{}s\] done
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B)
\[3.32\times {{10}^{34}}\,J\text{}s\] done
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C)
\[1.05\times {{10}^{34}}\,J\text{}s\] done
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D)
\[2.08\times {{10}^{34}}\,J\text{}s\] done
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In hydrogen atom, if the difference in the energy of the electron in \[n=2\] and \[n=3\] orbits is E, the ionization energy of hydrogen atom is
A)
13.2 E done
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B)
7.2 E done
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C)
5.6 E done
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D)
3.2 E done
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Orbital acceleration of electron is
A)
\[\frac{{{n}^{2}}{{h}^{2}}}{4{{\pi }^{2}}{{m}^{2}}{{r}^{3}}}\] done
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B)
\[\frac{{{n}^{2}}{{h}^{2}}}{2{{n}^{2}}{{r}^{3}}}\] done
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C)
\[\frac{4{{n}^{2}}{{h}^{2}}}{{{\pi }^{2}}{{m}^{2}}{{r}^{3}}}\] done
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D)
\[\frac{4{{n}^{2}}{{h}^{2}}}{4{{\pi }^{2}}{{m}^{2}}{{r}^{3}}}\] done
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The wavelength of light emitted from second orbit to first orbits in a hydrogen atom is
A)
\[1.215\times {{10}^{7}}m\] done
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B)
\[1.215\times {{10}^{5}}m\] done
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C)
\[1.215\times {{10}^{4}}m\] done
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D)
\[1.215\times {{10}^{3}}m\] done
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The possible quantum number for 3d electron are
A)
\[n=3,\,l=1,\,{{m}_{l}}=+1,\,{{m}_{s}}=\frac{1}{2}\] done
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B)
\[n=3,\,l=2,\,{{m}_{l}}=+2,\,{{m}_{s}}=\frac{1}{2}\] done
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C)
\[n=3,\,l=1,\,{{m}_{l}}=1,\,{{m}_{s}}=+\frac{1}{2}\] done
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D)
\[n=3,\,l=0,\,{{m}_{l}}=+1,\,{{m}_{s}}=\frac{1}{2}\] done
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Which of the following is quantised according to Bohrs theory of hydrogen atom
A)
Linear momentum of electron done
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B)
Angular momentum of electron done
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C)
Linear velocity of electron done
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D)
Angular velocity of electron done
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In Bohrs model of hydrogen atom, which of the following pairs of quantities are quantized
A)
Energy and linear momentum done
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B)
Linear and angular momentum done
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C)
Energy and angular momentum done
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D)
None of the above done
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What is the ratio of wavelength of radiations emitted when an electron in hydrogen atom jump from fourth orbit to second orbit and from third orbit to second orbit
A)
27 : 25 done
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B)
20 : 27 done
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C)
20 : 25 done
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D)
25 : 27 done
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In the following atoms and moleculates for the transition from n= 2 to n = 1, the spectral line of minimum wavelength will be produced by
A)
Hydrogen atom done
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B)
Deuterium atom done
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C)
Uniionized helium done
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D)
diionized lithium done
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The energy required to knock out the electron in the third orbit of a hydrogen atom is equal to
A)
\[13.6\ eV\] done
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B)
\[+\frac{13.6}{9}eV\] done
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C)
\[\frac{13.6}{3}eV\] done
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D)
\[\frac{3}{13.6}eV\] done
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The following diagram indicates the energy levels of a certain atom when the system moves from 2E level to E, a photon of wavelength \[\lambda \] is emitted. The wavelength of photon produced during its transition from \[\frac{4E}{3}\] level to E is
A)
\[\lambda /3\] done
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B)
\[3\lambda /4\] done
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C)
\[4\lambda /3\] done
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D)
\[3\lambda \] done
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The ratio of the kinetic energy to the total energy of an electron in a Bohr orbit is
A)
1 done
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B)
2 done
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C)
1 : 2 done
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D)
None of these done
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According to Bohr's theory, the expressions for the kinetic and potential energy of an electron revolving in an orbit is given respectively by
A)
\[+\frac{{{e}^{2}}}{8\pi {{\varepsilon }_{0}}r}\]and \[\frac{{{e}^{2}}}{4\pi {{\varepsilon }_{0}}r}\] done
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B)
\[+\frac{8\pi {{\varepsilon }_{0}}{{e}^{2}}}{r}\]and\[\frac{4\pi {{\varepsilon }_{0}}{{e}^{2}}}{r}\] done
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C)
\[\frac{{{e}^{2}}}{8\pi {{\varepsilon }_{0}}r}\]and \[\frac{{{e}^{2}}}{4\pi {{\varepsilon }_{0}}r}\] done
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D)
\[+\frac{{{e}^{2}}}{8\pi {{\varepsilon }_{0}}r}\]and \[+\frac{{{e}^{2}}}{4\pi {{\varepsilon }_{0}}r}\] done
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The velocity of an electron in the second orbit of sodium atom (atomic number = 11) is v. The velocity of an electron in its fifth orbit will be
A)
v done
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B)
\[\frac{22}{5}v\] done
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C)
\[\frac{5}{2}v\] done
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D)
\[\frac{2}{5}v\] done
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The extreme wavelengths of Paschen series are
A)
\[0.365\mu m\]and \[0.565\mu m\] done
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B)
\[0.818\mu m\]and \[1.89\mu m\] done
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C)
\[1.45\mu m\]and \[4.04\mu m\] done
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D)
\[2.27\mu m\]and \[7.43\mu m\] done
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The energy of a hydrogen atom in its ground state is \[13.6\ eV\]. The energy of the level corresponding to the quantum number n = 2 (first excited state) in the hydrogen atom is
A)
 2.72 eV done
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B)
 0.85 eV done
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C)
 0.54 eV done
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D)
 3.4 eV done
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The wavelength of the energy emitted when electron come from fourth orbit to second orbit in hydrogen is \[20.397\,cm\]. The wavelength of energy for the same transition in \[H{{e}^{+}}\] is
A)
\[5.099\ c{{m}^{1}}\] done
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B)
\[20.497\ c{{m}^{1}}\] done
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C)
\[40.994\ c{{m}^{1}}\] done
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D)
\[81.988\ c{{m}^{1}}\] done
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If \[{{\lambda }_{\max }}\] is 6563 \[\overset{\text{o}}{\mathop{\text{A}}}\,\], then wave length of second line for Balmer series will be
A)
\[\lambda =\frac{16}{3R}\] done
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B)
\[\lambda =\frac{36}{5R}\] done
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C)
\[\lambda =\frac{4}{3R}\] done
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D)
None of the above done
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The electron in a hydrogen atom makes a transition from an excited state to the ground state. Which of the following statements is true
A)
Its kinetic energy increases and its potential and total energies decrease done
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B)
Its kinetic energy decreases, potential energy increases and its total energy remains the same done
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C)
Its kinetic and total energies decrease and its potential energy increases done
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D)
Its kinetic, potential and total energies decreases done
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The first line in the Lyman series has wavelength l. The wavelength of the first line in Balmer series is
A)
\[\frac{2}{9}\lambda \] done
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B)
\[\frac{9}{2}\lambda \] done
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C)
\[\frac{5}{27}\lambda \] done
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D)
\[\frac{27}{5}\lambda \] done
clear
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