2025 Exam Questions
Q. Derive an expression for law of radioactive decay. Define one becquerel (Bq).
Q. An electron in hydrogen atom stays in its second orbit for 10^{-8} \mathrm{~s} . How many revolutions will it make around the nucleus in that time?
[Given: \mathrm{e}=1.6 \times 10^{-19} \mathrm{C}, \mathrm{m}=9.1 \times 10^{-31} \mathrm{~kg} ]
2024 Exam Questions
Q. What is binding energy of a hydrogen atom?
Q. Calculate the change in angular momentum of electron when it jumps fromt third orbit to first orbit in hydrogen atom.
Q.Calculate the wavelength of the first two lines in Balmer series of hydrogen atom.
2023 Exam Questions
Q. The radius of eighth orbit of electron in H-atom will be more than that of fourth orbit by a factor of ____.
(A) 2
(B) 4
(C) 8
(D) 16
Q. State postulates of Bohr’s atomic model.
Q. Disintegration rate of a radio-active sample is 1010 per hour at 20 hours from the start. It reduces to 5 x 109 per hour after 30 hours. Calculate the decay constant.
2022 Exam Questions
Q. Balmer series is obtained when all transitions of electron terminate on ______.
(A) 2nd orbit
(B) 1st orbit
(C) 3rd orbit
(D) 4th orbit
Q. What is the mathematical formula for third postulate of Bohr’s atomic model?
Q. Derive an expression for the radius of the nth Bohr orbit of the electron in hydrogen atom.
Q. State the first and second postulate of Bohr’s atomic model.
Q. Determine the shortest wavelengths of Balmer and Paschen series. Given the limit for Lyman series is 912\;\overset oA.
Q. Compute the ratio of longest wavelengths of Lyman and Balmer series in hydrogen atom.
Q. The half-life of a nuclear species is 1.386 years. Calculate its decay constant per year.
