1
JEE Main 2022 (Online) 29th July Morning Shift
+4
-1 Match List - I with List - II :

List - I List - II
(a) UV rays (i) Diagnostic tool in medicine
(b) X-rays (ii) Water purification
(d) Infrared wave (iv) Improving visibility in foggy days

Choose the correct answer from the options given below :

A
(a)-(iii), (b)-(ii), (c)-(i), (d)-(iv)
B
(a)-(ii), (b)-(i), (c)-(iii), (d)-(iv)
C
(a)-(ii), (b)-(iv), (c)-(iii), (d)-(i)
D
(a)-(iii), (b)-(i), (c)-(ii), (d)-(iv)
2
JEE Main 2022 (Online) 29th July Morning Shift
+4
-1 Find the ratio of energies of photons produced due to transition of an electron of hydrogen atom from its (i) second permitted energy level to the first level, and (ii) the highest permitted energy level to the first permitted level.

A
3 : 4
B
4 : 3
C
1 : 4
D
4 : 1
3
JEE Main 2022 (Online) 28th July Evening Shift
+4
-1 A radioactive sample decays $$\frac{7}{8}$$ times its original quantity in 15 minutes. The half-life of the sample is

A
5 min
B
7.5 min
C
15 min
D
30 min
4
JEE Main 2022 (Online) 28th July Morning Shift
+4
-1 The equation $$\lambda=\frac{1.227}{x} \mathrm{~nm}$$ can be used to find the de-Brogli wavelength of an electron. In this equation $$x$$ stands for :

Where

$$\mathrm{m}=$$ mass of electron

$$\mathrm{P}=$$ momentum of electron

$$\mathrm{K}=$$ Kinetic energy of electron

$$\mathrm{V}=$$ Accelerating potential in volts for electron

A
$$\sqrt{\mathrm{mK}}$$
B
$$\sqrt{\mathrm{P}}$$
C
$$\sqrt{\mathrm{K}}$$
D
$$\sqrt{\mathrm{V}}$$
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