JEE Main 2025 (Online) 4th April Morning Shift | Atoms and Nuclei Question 7 | Physics

1

JEE Main 2025 (Online) 4th April Morning Shift

MCQ (Single Correct Answer)

+4

-1

Considering the Bohr model of hydrogen like atoms, the ratio of the radius of $5^{\text {th }}$ orbit of the electron in $\mathrm{Li}^{2+}$ and $\mathrm{He}^{+}$is

A

$\frac{3}{2}$

B

$\frac{2}{3}$

C

$\frac{4}{9}$

D

$\frac{9}{4}$

2

JEE Main 2025 (Online) 3rd April Evening Shift

MCQ (Single Correct Answer)

+4

-1

Given below are two statements: one is labelled as $\mathbf{A s s e r t i o n} \mathbf{A}$ and the other is labelled as Reason $\mathbf{R}$

Assertion A : The Bohr model is applicable to hydrogen and hydrogen-like atoms only.

Reason $\mathbf{R}$ : The formulation of Bohr model does not include repulsive force between electrons.

In the light of the above statements, choose the correct answer from the options given below

A

$\mathbf{A}$ is true but $\mathbf{R}$ is false

B

Both $\mathbf{A}$ and $\mathbf{R}$ are true and $\mathbf{R}$ is the correct explanation of $\mathbf{A}$

C

$\mathbf{A}$ is false but $\mathbf{R}$ is true

D

Both $\mathbf{A}$ and $\mathbf{R}$ are true but $\mathbf{R}$ is NOT the correct explanation of $\mathbf{A}$

3

JEE Main 2025 (Online) 3rd April Morning Shift

MCQ (Single Correct Answer)

+4

-1

$$ \text { Match the LIST-I with LIST-II } $$

List - I		List - II
A.	$$ { }_0^1 \mathrm{n}+{ }_{92}^{235} \mathrm{U} \rightarrow{ }_{54}^{140} \mathrm{Xe}+{ }_{38}^{94} \mathrm{Sr}+2{ }_0^1 \mathrm{n} $$	I.	$$ \text { Chemical reaction } $$
B.	$$ 2 \mathrm{H}_2+\mathrm{O}_2 \rightarrow 2 \mathrm{H}_2 \mathrm{O} $$	II.	$$ \text { Fusion with +ve } \mathrm{Q} \text { value } $$
C.	$$ { }_1^2 \mathrm{H}+{ }_1^2 \mathrm{H} \rightarrow{ }_2^3 \mathrm{He}+{ }_0^1 \mathrm{n} $$	III.	$$ \text { Fission } $$
D.	$$ { }_1^1 \mathrm{H}+{ }_1^3 \mathrm{H} \rightarrow{ }_1^2 \mathrm{H}+{ }_1^2 \mathrm{H} $$	IV.	$$ \text { Fusion with -ve } Q \text { value } $$

$$ \text { Choose the correct answer from the options given below: } $$

A

A-II, B-I, C-III, D-IV

B

A-III, B-I, C-II, D-IV

C

A-III, B-I, C-IV, D-II

D

A-II, B-I, C-IV, D-III

4

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