MHT CET 2025 19th April Morning Shift | Atoms and Nuclei Question 6 | Physics

If ' $\lambda_1$ ' and ' $\lambda_2$ ' are the wavelengths of the first member of the Balmer and Paschen series, in hydrogen atom respectively, then the ratio of respective frequencies, $f_1 / f_2$, is

$20: 7$

$27: 5$

$50: 9$

$108: 7$

MHT CET 2025 19th April Morning Shift

MCQ (Single Correct Answer)

-0

The ratio of the wavelength of the last line of Paschen series to that of Balmer series is

$\frac{9}{4}$

$\frac{3}{2}$

$\frac{2}{3}$

$\frac{4}{9}$

MHT CET 2024 16th May Evening Shift

MCQ (Single Correct Answer)

-0

In the second orbit of hydrogen atom, the energy of an electron is ' $E$ '. In the third orbit of helium atom, the energy of the electron will be (atomic number of helium $=2$)

$\frac{4 \mathrm{E}}{9}$

$\frac{4 \mathrm{E}}{3}$

$\frac{16 \mathrm{E}}{9}$

$\frac{16 \mathrm{E}}{3}$

MHT CET 2024 16th May Evening Shift

MCQ (Single Correct Answer)

-0

Two radioactive substances A and B have decay constants ' $5 \lambda$ ' and ' $\lambda$ ' respectively. At $\mathrm{t}=0$, they have the same number of nuclei. The ratio of number of nuclei of $A$ to those of $B$ will be $\left(\frac{1}{\mathrm{e}}\right)^2$ after a time interval

$\frac{1}{42}$

$4 \lambda$

$2 \lambda$

$\frac{1}{2 \lambda}$

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