1
JEE Main 2023 (Online) 15th April Morning Shift
+4
-1
Out of Syllabus
The half-life of a radioactive nucleus is 5 years. The fraction of the original sample that would decay in 15 years is:
A
$\frac{1}{8}$
B
$\frac{3}{4}$
C
$\frac{7}{8}$
D
$\frac{1}{4}$
2
JEE Main 2023 (Online) 13th April Evening Shift
+4
-1
Out of Syllabus

Given below are two statements: one is labelled as Assertion $$\mathbf{A}$$ and the other is labelled as Reason $$\mathbf{R}$$

Assertion A : The binding energy per nucleon is practically independent of the atomic number for nuclei of mass number in the range 30 to 170 .

Reason R : Nuclear force is short ranged.

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

A
$$\mathrm{A}$$ is false but $$\mathbf{R}$$ is true
B
$$\mathrm{A}$$ is true but $$\mathbf{R}$$ is false
C
Both $$\mathbf{A}$$ and $$\mathbf{R}$$ are true and $$\mathbf{R}$$ is the correct explanation of $$\mathbf{A}$$
D
Both $$\mathbf{A}$$ and $$\mathbf{R}$$ are true but $$\mathbf{R}$$ is NOT the correct explanation of $$\mathbf{A}$$
3
JEE Main 2023 (Online) 13th April Morning Shift
+4
-1

$$_{92}^{238}A \to _{90}^{234}B + _2^4D + Q$$

In the given nuclear reaction, the approximate amount of energy released will be:

[Given, mass of $${ }_{92}^{238} \mathrm{~A}=238.05079 \times 931.5 ~\mathrm{MeV} / \mathrm{c}^{2},$$

mass of $${ }_{90}^{234} B=234 \cdot 04363 \times 931 \cdot 5 ~\mathrm{MeV} / \mathrm{c}^{2},$$

mass of $$\left.{ }_{2}^{4} D=4 \cdot 00260 \times 931 \cdot 5 ~\mathrm{MeV} / \mathrm{c}^{2}\right]$$

A
2.12 MeV
B
4.25 MeV
C
3.82 MeV
D
5.9 MeV
4
JEE Main 2023 (Online) 12th April Morning Shift
+4
-1

A $$12.5 \mathrm{~eV}$$ electron beam is used to bombard gaseous hydrogen at room temperature. The number of spectral lines emitted will be:

A
2
B
4
C
3
D
1
EXAM MAP
Medical
NEET