Many important questions are formed in competitive exams like CUET, JEE, NEET, and boards from Class 12 Physics. Below, we have provided Important Questions from Class 12 Physics Unit 8, Atoms and Nuclei for your JEE Mains 2023 preparation. You can check it here for revision purposes.
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Atoms and Nuclei Class 12 JEE Mains Questions and Answers
Weโve compiled a list of important questions about the Atoms and Nuclei Class 12 physics unit 8 that you should not miss while studying for your JEE Main Exams.
Q.1.ย A hydrogen-like atom (atomic number Z) is in a higher excited state of quantum number n. This excited atom can make a transition to the first excited state by successively emitting two photons of energies 10.20 eV and 17.00 eV respectively. Alternatively, the atom from the same excited state can make a transition to the second excited state by successively emitting two photons of energies 4.25 eV and 5.95 eV respectively. Determine the value of n. (Ionisation energy of hydrogen atom = 13.6 eV)
(a) n = 6 (b) n = 4 (c) n = 7 (d) n = 3
A.1. (a)
Q.2.ย Protons and singly ionized atoms of U235 and U238 are passed in turn (which means one after the other and not at the same time) through a velocity selector and then enter a uniform magnetic field. The protons describe semicircles of radius 10 mm. The separation between the ions of U235 and U238 after describing semicircle is given byย
(a) 60 mm (b) 30 mm
(c) 2350 mm (d) 2380 mm
A.2. (a)
Q.3.ย Which of the following products in a hydrogen atom are independent of the principal quantum number n? The symbols have their usual meanings.
(a) vn (b) Er (c) En (d) vr
A.3. (a,b)
Q.4.ย Hydrogen atom in its ground state is excited by means of monochromatic radiation of wavelength 970.6 ร . How many different wavelengths are possible in the resulting emission spectrum?
A.4. (6)
Q.5.ย Starting with a sample of pure 66Cu, 7/8 of it decays into Zn in 15 minutes. Find the corresponding half-life (in minutes).
A.5. (5)
Q.6.ย An โ-particle and a proton are accelerated from rest by a potential difference of 100 V. After this, their de Broglie wavelengths are ฮปa and ฮปp respectively. Find the ratio ฮปpย / ฮปโ, to the nearest integer.
A.6. (3)
Comprehension Type
The key feature of Bohrโs theory of the spectrum of hydrogen atom is the quantization of angular momentum when an electron is revolving around a proton. We will extend this to a general rotational motion to find the quantized rotational energy of a diatomic molecule assuming it to be rigid. The rule to be applied is Bohrโs quantization condition.
Q.1.
A.1. (d)
Q.2.ย
A.2. (b)
ย
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