1
JEE Main 2023 (Online) 29th January Morning Shift
MCQ (Single Correct Answer)
+4
-1
Out of Syllabus
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If a radioactive element having half-life of $$30 \mathrm{~min}$$ is undergoing beta decay, the fraction of radioactive element remains undecayed after $$90 \mathrm{~min}$$. will be

A
$$\frac{1}{16}$$
B
$$\frac{1}{4}$$
C
$$\frac{1}{8}$$
D
$$\frac{1}{2}$$
2
JEE Main 2023 (Online) 25th January Evening Shift
MCQ (Single Correct Answer)
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-1
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The energy levels of an atom is shown in figure.

JEE Main 2023 (Online) 25th January Evening Shift Physics - Atoms and Nuclei Question 50 English

Which one of these transitions will result in the emission of a photon of wavelength 124.1 nm?

Given (h = 6.62 $$\times$$ 10$$^{-34}$$ Js)

A
C
B
B
C
A
D
D
3
JEE Main 2023 (Online) 25th January Morning Shift
MCQ (Single Correct Answer)
+4
-1
Out of Syllabus
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The ratio of the density of oxygen nucleus ($$_8^{16}O$$) and helium nucleus ($$_2^{4}\mathrm{He}$$) is

A
4 : 1
B
1 : 1
C
2 : 1
D
8 : 1
4
JEE Main 2023 (Online) 24th January Evening Shift
MCQ (Single Correct Answer)
+4
-1
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A photon is emitted in transition from n = 4 to n = 1 level in hydrogen atom. The corresponding wavelength for this transition is (given, h = 4 $$\times$$ 10$$^{-15}$$ eVs) :

A
99.3 nm
B
94.1 nm
C
974 nm
D
941 nm
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