1
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 144 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.
2
JEE Main 2020 (Online) 6th September Evening Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
Given the masses of various atomic particles
mp = 1.0072 u, mn = 1.0087 u, me = 0.000548 u,
$${m_{\overline v }}$$ = 0, md = 2.0141 u, where p $$ \equiv $$ proton, n $$ \equiv $$ neutron,
e $$ \equiv $$ electron, $$\overline v $$ $$ \equiv $$ antineutrino and d $$ \equiv $$ deuteron. Which of the following process is allowed by momentum and energy conservation?
A
n + n $$ \to $$ deuterium atom
(electron bound to the nucleus)
B
n + p $$ \to $$ d + $$\gamma $$
C
p $$ \to $$ n + e+ + $$\overline v $$
D
e+ + e- $$ \to $$ $$\gamma $$
3
JEE Main 2020 (Online) 6th September Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
You are given that Mass of $${}_3^7Li$$ = 7.0160u,
Mass of $${}_2^4He$$ = 4.0026u
and Mass of $${}_1^1H$$ = 1.0079u.
When 20 g of $${}_3^7Li$$ is converted into $${}_2^4He$$ by proton capture, the energy liberated, (in kWh), is :
[Mass of nucleon = 1 GeV/c2]
A
6.82 $$ \times $$ 105
B
4.5 $$ \times $$ 105
C
8 $$ \times $$ 106
D
1.33 $$ \times $$ 106
4
JEE Main 2020 (Online) 5th September Evening Slot
MCQ (Single Correct Answer)
+4
-1
Out of Syllabus
Change Language
A radioactive nucleus decays by two different processes. The half life for the first process is 10 s and that for the second is 100 s. The effective half life of the nucleus is close to :
A
12 sec
B
9 sec
C
55 sec
D
6 sec
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