MHT CET 2025 25th April Evening Shift | Atoms and Nuclei Question 3 | Physics

In hydrogen atom in its ground state, the first Bohr orbit has radius ' $\mathrm{r}_1$ '. When the atom is raised to one of its excited states, the electrons orbital velocity becomes one-third. The radius of that orbit is

$2 r_1$

$3 r_1$

$4 r_1$

$9 r_1$

MHT CET 2025 25th April Morning Shift

MCQ (Single Correct Answer)

-0

A radioactive element has rate of disintegration 9000 disintegration per minute at a particular instant. After two minutes it becomes 3000 disintegration per minute. The decay constant per minute is

$0.5 \log _{\mathrm{c}} 3$

$0.2 \log _{\mathrm{e}} 3$

$0.5 \log _{\mathrm{e}} 2$

$0.2 \log _{\mathrm{e}} 2$

MHT CET 2025 23rd April Evening Shift

MCQ (Single Correct Answer)

-0

In hydrogen atom, transition from the state $\mathrm{n}=6$ to $n=1$ results in ultraviolet radiation. Infrared radiation will be obtained in the transition

$\mathrm{n}=3$ to $\mathrm{n}=1$

$\mathrm{n}=4$ to $\mathrm{n}=2$

$n=6$ to $n=2$

$n=5$ to $n=3$

MHT CET 2025 23rd April Evening Shift

MCQ (Single Correct Answer)

-0

A radioactive element ${ }_{92}^{242} \mathrm{X}$ emits two $\alpha$ particles, one electron and two positrons. The product nucleus is represented by ${ }_{\mathrm{p}}^{234} \mathrm{Y}$. The value of $P$ is

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