1
JEE Main 2025 (Online) 2nd April Evening Shift
MCQ (Single Correct Answer)
+4
-1
Energy released when two deuterons $\left({ }_1 \mathrm{H}^2\right)$ fuse to form a helium nucleus $\left({ }_2 \mathrm{He}^4\right)$ is : (Given : Binding energy per nucleon of ${ }_1 \mathrm{H}^2=1.1 \mathrm{MeV}$ and binding energy per nucleon of ${ }_2 \mathrm{He}^4=7.0 \mathrm{MeV}$ )
A
26.8 MeV
B
8.1 MeV
C
23.6 MeV
D
5.9 MeV
2
JEE Main 2025 (Online) 2nd April Evening Shift
MCQ (Single Correct Answer)
+4
-1
Assuming the validity of Bohr's atomic model for hydrogen like ions the radius of $\mathrm{Li}^{++}$ ion in its ground state is given by $\frac{1}{X} a_0$, where $X=$ __________ (Where $\mathrm{a}_0$ is the first Bohr's radius.)
A
2
B
9
C
1
D
3
3
JEE Main 2025 (Online) 2nd April Morning Shift
MCQ (Single Correct Answer)
+4
-1

Considering Bohr's atomic model for hydrogen atom :

(A) the energy of H atom in ground state is same as energy of $\mathrm{He}^{+}$ion in its first excited state.

(B) the energy of H atom in ground state is same as that for $\mathrm{Li}^{++}$ ion in its second excited state.

(C) the energy of H atom in its ground state is same as that of $\mathrm{He}^{+}$ion for its ground state.

(D) the energy of $\mathrm{He}^{+}$ion in its first excited state is same as that for $\mathrm{Li}^{++}$ion in its ground state.

Choose the correct answer from the options given below :

A
(A), (B) only
B
(A), (D) only
C
(A), (C) only
D
(B), (D) only
4
JEE Main 2025 (Online) 29th January Evening Shift
MCQ (Single Correct Answer)
+4
-1
Change Language

The number of spectral lines emitted by atomic hydrogen that is in the 4th energy level, is

A

3

B

6

C

1

D

0

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