Dual Nature, Atoms & Nuclei · JEE Main previous year questions

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2024 40 questions

Q572024 · 31 Jan 2024 · Shift 1· Numerical answer
The mass defect in a particular reaction is $0.4 g$ . The amount of energy liberated is $n \times 1 0^{7} kWh$ , where $n =$ ____. (speed of light $= 3 \times 1 0^{8} m/s$ )
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Answer: 1
Q332024 · 31 Jan 2024 · Shift 2
In a photoelectric effect experiment a light of frequency 1.5 times the threshold frequency is made to fall on the surface of photosensitive material. Now if the frequency is halved and intensity is doubled, the number of photo electrons emitted will be:
1. A.doubled
2. B.halved
3. C.Zero
4. D.quadrupled
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Answer: C
Q342024 · 31 Jan 2024 · Shift 2
The mass number of nucleus having radius equal to half of the radius of nucleus with mass number 192 is :
1. A.32
2. B.24
3. C.20
4. D.40
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Answer: B
Q572024 · 31 Jan 2024 · Shift 2· Numerical answer
A nucleus has mass number $A_{1}$ and volume $V_{1}$ . Another nucleus has mass number $A_{2}$ and Volume $V_{2}$ . If relation between mass number is $A_{2} = 4 A_{1}$ , then $\frac{V _{2}}{V _{1}} =$ ____.
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Answer: 4
Q322024 · 30 Jan 2024 · Shift 1
The work function of a substance is $3.0 eV$ . The longest wavelength of light that can cause the emission of photoelectrons from this substance is approximately;
1. A. $215 nm$
2. B. $400 nm$
3. C. $414 nm$
4. D. $200 nm$
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Answer: C
Q532024 · 30 Jan 2024 · Shift 1· Numerical answer
An electron of hydrogen atom in an excited state is having energy $E_{n} = - 0.85 eV$ . The maximum number of allowed transitions to lower energy level is _________.
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Answer: 6
Q322024 · 29 Jan 2024 · Shift 1
The de-Broglie wavelength of an electron is the same as that of a photon. If velocity of electron is $25%$ of the velocity of light, then the ratio of K.E. of electron and K.E. of photon will be:
1. A. $\frac{1}{4}$
2. B. $\frac{8}{1}$
3. C. $\frac{1}{8}$
4. D. $\frac{1}{1}$
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Answer: C
Q502024 · 29 Jan 2024 · Shift 1
The explosive in a Hydrogen bomb is a mixture of $_{1} H^{2},_{1} H^{3}$ and $_{3} Li^{6}$ in some condensed form. The chain reaction is given by $_{3} Li^{6} +_{0} n^{1} \to_{2} He^{4} +_{1} H^{3}$ $_{1} H^{2} +_{1} H^{3} \to_{2} He^{4} +_{0} n^{1}$ During the explosion the energy released is approximately [Given ; $M(Li) = 6.01690 amu$ , $M (_{1} H^{2}) = 2.01471 amu$ , $M (_{2} He^{4}) = 4.00388 amu$ , and $1 amu = 931.5 MeV$ ]
1. A. $22.22 MeV$
2. B. $28.12 MeV$
3. C. $16.48 MeV$
4. D. $12.64 MeV$
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Answer: A
Q542024 · 29 Jan 2024 · Shift 1· Numerical answer
When a hydrogen atom going from $n = 2$ to $n = 1$ emits a photon, its recoil speed is $\frac{x}{5} m/s$ . Where $x =$ _______. (Use, mass of hydrogen atom $= 1.6 \times 1 0^{- 27} kg$ )
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Answer: 17
Q482024 · 29 Jan 2024 · Shift 2
Given below are two statements: Statement I : Most of the mass of the atom and all its positive charge are concentrated in a tiny nucleus and the electrons revolve around it, is Rutherford's model. Statement II : An atom is a spherical cloud of positive charges with electrons embedded in it, is a special case of Rutherford's model. In the light of the above statements, choose the most appropriate from the options given below
1. A.Both Statement I and Statement II are true
2. B.Statement I is true but Statement II is false
3. C.Statement I is false but Statement II is true
4. D.Both statement I and statement II are false
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Answer: B
Q492024 · 29 Jan 2024 · Shift 2
Two sources of light emit with a power of $200 W$ . The ratio of number of photons of visible light emitted by each source having wavelengths $300 nm$ and $500 nm$ respectively, will be :
1. A. $5 : 3$
2. B. $3 : 5$
3. C. $1 : 5$
4. D. $1 : 3$
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Answer: B
Q552024 · 29 Jan 2024 · Shift 2· Numerical answer
Hydrogen atom is bombarded with electrons accelerated through a potential difference of V, which causes excitation of hydrogen atoms. If the experiment is being performed at $T = 0 K$ , the minimum potential difference needed to observe any Balmer series lines in the emission spectra will be $\frac{α}{10} V$ , where $α =$ _________.
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Answer: 121
Q552024 · 27 Jan 2024 · Shift 1· Numerical answer
In a nuclear fission process, a high mass nuclide ( $A \approx 236$ ) with binding energy $7.6 MeV/ Nucleon$ dissociated into middle mass nuclides ( $A \approx 118$ ), having binding energy of $8.6 MeV/Nucleon$ . The energy released in the process would be _____ $MeV$ .
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Answer: 236
Q392024 · 27 Jan 2024 · Shift 2
The threshold frequency of a metal with work function $6.63 eV$ is :
1. A. $16 \times 1 0^{15} Hz$
2. B. $16 \times 1 0^{12} Hz$
3. C. $1.6 \times 1 0^{15} Hz$
4. D. $1.6 \times 1 0^{12} Hz$
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Answer: C
Q562024 · 27 Jan 2024 · Shift 2· Numerical answer
The electric potential at the surface of an atomic nucleus ( $z = 50$ ) of radius $9 \times 1 0^{- 13} cm$ is _______ $\times 1 0^{6} V$ .
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Answer: 8