De-Broglie wavelength of an electron orbiting in the \(n=2\) state of a hydrogen atom is close to: (given: Bohr radius \(=0.052~ \text{nm}\))
1. \(1.67~ \text{nm}\) 2. \(2.67~ \text{nm}\)
3. \(0.067~ \text{nm}\) 4. \(0.67~ \text{nm}\)
Subtopic:  De-broglie Wavelength |
Level 3: 35%-60%
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A photon and an electron (of mass \(m\)) have the same total energy \(E. \) If \(c\) denotes the speed of light, what is the ratio of their de-Broglie wavelengths \((\lambda_{\text{photon}}/\lambda_{\text{electron}})\text{?} \)

1. \(c\sqrt{\dfrac{2m}{E}} \) 2. \(\dfrac{1}{c}\sqrt{\dfrac{E}{2m}}\)
3. \(\sqrt{\dfrac{E}{2m}}\) 4. \(c\sqrt{2mE}\)
Subtopic:  De-broglie Wavelength |
Level 3: 35%-60%
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A particle of mass \(m\) is moving around the origin with a constant force \(F\) pulling it towards the origin. If Bohr model is used to describe its motion, the radius \(r\) of the \(n^{\text{th}}\) orbit and the particle's speed \(v\) in the orbit depend on \(n\) as:
1. \(r \propto n^{2/3}; v \propto n^{1/3}\) 2. \(r \propto n^{4/3}; v \propto n^{-1/3}\)
3. \(r \propto n^{1/3}; v \propto n^{1/3}\) 4. \(r \propto n^{1/3}; v \propto n^{2/3}\)
Subtopic:  Bohr's Model of Atom |
Level 3: 35%-60%
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A full wave rectifier circuit with diodes \((D_1)\) and \((D_2)\) is shown in the figure. If input supply voltage \(V_{\text{in}}=220\sin(100\pi t)\) volt, then at \(t=15~\text{ms}\text{:}\)
1. \(D_1\) and \(D_2\) both are forward biased
2. \(D_1\) and \(D_2\) both are reverse biased
3. Neither \(D_1\)​ nor \(D_2\)​ conducts at any time
4. \(D_1\) is reverse biased, \(D_2\) is forward biased
Subtopic:  Rectifier |
Level 3: 35%-60%
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The output \(Y \) of the given logic implementation is similar to the output of which gate?
1. OR 2. NOR
3. AND 4. NAND
Subtopic:  Logic gates |
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Atomic theory could not explain which of the following?
1. Law of multiple proportion 2. Law of gaseous volume
3. Law of conservation of mass 4. Law of constant proportion
Subtopic:  Introduction |
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Consider the following data of compounds:
A. \(212 ~g ~\text{of}~Na_2CO_3 (s) \text{[molar mass}=106 ~g]\)
B. \(~248 g ~\text{of}~ {Na}_2 \mathrm{O}({s}) [\text{molar mass} =62 \mathrm{~g} ]\)
C. \(240 g ~\text{of} ~NaOH (s)~ [\text{molar mass} =40 \mathrm{~g} \)
D. \( 12 g~ \text{of}~ \mathrm{H}_2(\mathrm{~g})[ \text{molar mass} =2 \mathrm{~g}].\)
E. \( 220 g~ \text{of} ~\mathrm{CO}_2(\mathrm{~g})[\text{ molar mass }=44 \mathrm{~g}]\)
Which of the following represents a correct set of compounds having an equal number of atoms?
1. B, C, and D only 2. B, D, and E only
3. A, B, and C only 4. A, B, and D only
Subtopic:  Moles, Atoms & Electrons |
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The ratio of the wavelengths of the light absorbed by a Hydrogen atom when it undergoes \(n=2 \rightarrow n=3\) and \(n=4 \rightarrow n=6\) transitions, respectively, is
1. \(\dfrac{1}{9}\) 2. \(\dfrac{1}{4}\)
3. \(\dfrac{1}{36}\) 4. \(\dfrac{1}{16}\)
Subtopic:  Hydrogen Spectra |
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Level 2: 60%+
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Energy and radius of the first Bohr orbit of He+ and Li2+ are: [Given \(\left.\mathrm{R}_{\mathrm{H}}=2.18 \times 10^{-18} \mathrm{~J}, \mathrm{a}_0=52.9 \mathrm{pm}\right]\)
1. \(\begin{aligned} & \mathrm{E}_{\mathrm{n}}\left(\mathrm{Li}^{2+}\right)=-19.62 \times 10^{-16} \mathrm{~J} ; \\ & \mathrm{r}_{\mathrm{n}}\left(\mathrm{Li}^{2+}\right)=17.6\mathrm{pm} \\ & \mathrm{E}_{\mathrm{n}}\left(\mathrm{He}^{+}\right)=8.72 \times 10^{-16} \mathrm{~J} ; \\ & \mathrm{r}_{\mathrm{n}}\left(\mathrm{He}^{+}\right)=26.4 \mathrm{pm} \end{aligned}\)
2. \(\begin{aligned} & \mathrm{E}_{\mathrm{n}}\left(\mathrm{Li}^{2+}\right)=-8.72 \times 10^{-16} \mathrm{~J} ; \\ & \mathrm{r}_{\mathrm{n}}\left(\mathrm{Li}^{2+}\right)=17.6 \mathrm{pm} \\ & \mathrm{E}_{\mathrm{n}}\left(\mathrm{He}^{+}\right)=-19.62 \times 10^{-16} \mathrm{~J} ; \\ & \mathrm{r}_{\mathrm{n}}\left(\mathrm{He}^{+}\right)=17.6 \mathrm{pm} \end{aligned}\)
3. \(\begin{aligned} & \mathrm{E}_{\mathrm{n}}\left(\mathrm{Li}^{2+}\right)=- 19.62 \times 10^{-18} \mathrm{~J} \\ & \mathrm{r}_{\mathrm{n}}\left(\mathrm{Li}^{2+}\right)=17.6 \mathrm{pm} \\ & \mathrm{E}_{\mathrm{n}}\left(\mathrm{He}^{+}\right)=-8.72 \times 10^{-18} \mathrm{~J} \\ & \mathrm{r}_{\mathrm{n}}\left(\mathrm{He}^{+}\right)=26.4 \mathrm{pm} \end{aligned}\)
4. \(\begin{aligned} & \mathrm{E}_{\mathrm{n}}\left(\mathrm{Li}^{2+}\right)=-8.72 \times 10^{-18} \mathrm{~J} \\ & \mathrm{r}_{\mathrm{n}}\left(\mathrm{Li}^{2+}\right)=26.4 \mathrm{pm} \\ & \mathrm{E}_{\mathrm{n}}\left(\mathrm{He}^{+}\right)=-19.62 \times 10^{-18} \mathrm{~J} ; \\ & \mathrm{r}_{\mathrm{n}}\left(\mathrm{He}^{+}\right)=17.6 \mathrm{pm} \end{aligned} \)
Subtopic:  Bohr's Theory |
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Which of the following electronic configurations belong to the main group elements?
A \([\mathrm{Ne}] 3 \mathrm{~s}^1\) B \([\mathrm{Ar}] 3d^3 \mathrm{~4s}^2\)
C \([\mathrm{Kr}] 4 \mathrm{~d}^{10} 5 \mathrm{~s}^2 5 \mathrm{p}^5\) D \([\mathrm{Ar}] 3 \mathrm{~d}^{10} 4 \mathrm{~s}^1\)
E \(\mathrm{[R n] }5 f^0 6 d^2 7 s^2\)

Choose the correct answer from the option given below:
1. D and E only 2. A, C and D only
3. B and E only 4. A and C only
Subtopic:  Modern Periodic Table & Periodicity |
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Level 3: 35%-60%
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