Assertion (A): | Rydberg's constant does not vary with the mass number of a given element. |
Reason (R): | The reduced mass of the electron is dependent on the mass of the nucleus only. |
1. | Both (A) and (R) are true and (R) is the correct explanation of (A). |
2. | Both (A) and (R) are true but (R) is not the correct explanation of (A). |
3. | (A) is true but (R) is false. |
4. | Both (A) and (R) are false. |
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NEET MCQ Books for XIth & XIIth Physics, Chemistry & BiologyAssertion (A): | Bohr had to postulate that the electrons in stationary orbits around the nucleus do not radiate. |
Reason (R): | According to classical physics all accelerating electrons radiate. |
1. | Both (A) and (R) are True and (R) is the correct explanation of (A). |
2. | Both (A) and (R) are True but (R) is not the correct explanation of (A). |
3. | (A) is True but (R) is False. |
4. | Both (A) and (R) are False. |
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NEET MCQ Books for XIth & XIIth Physics, Chemistry & BiologyAssertion (A): | A hydrogen atom at the ground state cannot absorb a photon of energy 10 eV. |
Reason (R): | First excitation energy of the hydrogen atom is 10.2 eV. The hydrogen atom absorbs only those photons which provide it the excitation energy. |
1. | Both (A) and (R) are true and (R) is the correct explanation of (A). |
2. | Both (A) and (R) are true but (R) is not the correct explanation of (A). |
3. | (A) is true but (R) is false. |
4. | Both (A) and (R) are false. |
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NEET MCQ Books for XIth & XIIth Physics, Chemistry & BiologyAssertion (A): | Magnetic moment associated with an electron in hydrogen atom is quantized. |
Reason (R): | Magnetic moment associated with the electron is an integral multiple of Bohr's magneton but is independent of atomic number. |
1. | Both (A) and (R) are true and (R) is the correct explanation of (A). |
2. | Both (A) and (R) are true but (R) is not the correct explanation of (A). |
3. | (A) is true but (R) is false. |
4. | Both (A) and (R) are false. |
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NEET MCQ Books for XIth & XIIth Physics, Chemistry & BiologyAn ionised \(H\)-molecule consists of an electron and two protons. The protons are separated by a small distance of the order of angstrom. In the ground state:
(a) | the electron would not move in circular orbits. |
(b) | the energy would be \(2^{4}\) times that of a \(H\)-atom. |
(c) | the electron's orbit would go around the protons. |
(d) | the molecule will soon decay in a proton and a \(H\)-atom. |
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NEET MCQ Books for XIth & XIIth Physics, Chemistry & BiologyThe Bohr model for the spectra of a \(H\)-atom:
(a) | will not apply to hydrogen in the molecular form. |
(b) | will not be applicable as it is for a \(He\)-atom. |
(c) | is valid only at room temperature. |
(d) | predicts continuous as well as discrete spectral lines. |
1. | (a), (b) | 2. | (c), (d) |
3. | (b), (c) | 4. | (a), (d) |
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NEET MCQ Books for XIth & XIIth Physics, Chemistry & BiologyLet \(E_{n} = \dfrac{- 1}{8 \varepsilon_{0}^{2}} \dfrac{m e^{4}}{n^{2} h^{2}}\) be the energy of the \(n^\text{th}\) level of H-atom. If all the H-atoms are in the ground state and radiation of frequency \(\dfrac{\left(\right. E_{2} - E_{1} \left.\right)}{h}\) falls on it, then:
(a) | it will not be absorbed at all. |
(b) | some of the atoms will move to the first excited state. |
(c) | all atoms will be excited to the \(n = 2\) state. |
(d) | no atoms will make a transition to the \(n = 3\) state. |
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NEET MCQ Books for XIth & XIIth Physics, Chemistry & BiologyThe simple Bohr model is not applicable to \(\text{He}^4\) atom because:
(a) | \(\text{He}^4\) is an inert gas. |
(b) | \(\text{He}^4\) has neutrons in the nucleus. |
(c) | \(\text{He}^4\) has one more electron. |
(d) | electrons are not subject to central forces. |
Choose the correct option:
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NEET MCQ Books for XIth & XIIth Physics, Chemistry & BiologyAssertion (A): | \(n.\) | The magnetic moment of a hydrogen-like atom is higher when it is in a state of higher quantum number
Reason (R): | \(n.\) | The magnetic moment of hydrogen-like atom, as calculated from Bohr's theory, is directly proportional to the principal quantum number
1. | (A) is True but (R) is False. |
2. | (A) is False but (R) is True. |
3. | Both (A) and (R) are True and (R) is the correct explanation of (A). |
4. | Both (A) and (R) are True but (R) is not the correct explanation of (A). |
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NEET MCQ Books for XIth & XIIth Physics, Chemistry & BiologyPrefer Books for Question Practice? Get NEETprep's Unique MCQ Books with Online Audio/Video/Text Solutions via Telegram Bot
NEET MCQ Books for XIth & XIIth Physics, Chemistry & Biology