1
JEE Main 2021 (Online) 25th February Evening Shift
MCQ (Single Correct Answer)
+4
-1
Change Language
The wavelength of the photon emitted by a hydrogen atom when an electron makes a transition from n = 2 to n = 1 state is :
A
194.8 nm
B
490.7 nm
C
913.3 nm
D
121.8 nm
2
JEE Main 2021 (Online) 25th February Morning Shift
MCQ (Single Correct Answer)
+4
-1
Out of Syllabus
Two radioactive substances X and Y originally have N1 and N2 nuclei respectively. Half life of X is half of the half life of Y. After three half lives of Y, number of nuclei of both are equal. The ratio $${{{N_1}} \over {{N_2}}}$$ will be equal to :
A
$${1 \over 8}$$
B
$${3 \over 1}$$
C
$${1 \over 3}$$
D
$${8 \over 1}$$
3
JEE Main 2021 (Online) 24th February Evening Shift
MCQ (Single Correct Answer)
+4
-1
Change Language
According to Bohr atomic model, in which of the following transitions will the frequency be maximum?
A
n = 2 to n = 1
B
n = 3 to n = 2
C
n = 4 to n = 3
D
n = 5 to n = 4
4
JEE Main 2021 (Online) 24th February Morning Shift
MCQ (Single Correct Answer)
+4
-1
Change Language
In the given figure, the energy levels of hydrogen atom have been shown along with some transitions marked A, B, C, D and E.

The transitions A, B and C respectively represent :

JEE Main 2021 (Online) 24th February Morning Shift Physics - Atoms and Nuclei Question 137 English
A
The series limit of Lyman series, second member of Balmer series and second member of Paschen series.
B
The ionization potential of hydrogen, second member of Balmer series and third member of Paschen series.
C
The series limit of Lyman series, third member of Balmer series and second member of Paschen series.
D
The first member of the Lyman series, third member of Balmer series and second member of Paschen series.
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