1
JEE Main 2023 (Online) 8th April Evening Shift
+4
-1
Out of Syllabus

A radio active material is reduced to $$1 / 8$$ of its original amount in 3 days. If $$8 \times 10^{-3} \mathrm{~kg}$$ of the material is left after 5 days the initial amount of the material is

A
64 g
B
256 g
C
32 g
D
40 g
2
JEE Main 2023 (Online) 8th April Evening Shift
+4
-1

The waves emitted when a metal target is bombarded with high energy electrons are

A
Infrared rays
B
C
Microwaves
D
X-rays
3
JEE Main 2023 (Online) 8th April Morning Shift
+4
-1

For a nucleus $${ }_{\mathrm{A}}^{\mathrm{A}} \mathrm{X}$$ having mass number $$\mathrm{A}$$ and atomic number $$\mathrm{Z}$$

A. The surface energy per nucleon $$\left(b_{\mathrm{s}}\right)=-a_{1} A^{2 / 3}$$.

B. The Coulomb contribution to the binding energy $$\mathrm{b}_{\mathrm{c}}=-a_{2} \frac{Z(Z-1)}{A^{4 / 3}}$$

C. The volume energy $$\mathrm{b}_{\mathrm{v}}=a_{3} A$$

D. Decrease in the binding energy is proportional to surface area.

E. While estimating the surface energy, it is assumed that each nucleon interacts with 12 nucleons. ( $$a_{1}, a_{2}$$ and $$a_{3}$$ are constants)

Choose the most appropriate answer from the options given below:

A
C, D only
B
B, C, E only
C
B, C only
D
A, B, C, D only
4
JEE Main 2023 (Online) 6th April Evening Shift
+4
-1

A small particle of mass $$m$$ moves in such a way that its potential energy $$U=\frac{1}{2} m ~\omega^{2} r^{2}$$ where $$\omega$$ is constant and $$r$$ is the distance of the particle from origin. Assuming Bohr's quantization of momentum and circular orbit, the radius of $$n^{\text {th }}$$ orbit will be proportional to,

A
$$\sqrt{n}$$
B
$$n^{2}$$
C
$$\frac{1}{n}$$
D
$$n$$
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