1
JEE Main 2021 (Online) 25th February Morning Slot
+4
-1
An $$\alpha$$ particle and a proton are accelerated from rest by a potential difference of 200V. After this, their de Broglie wavelengths are $$\lambda$$$$\alpha$$ and $$\lambda$$p respectively. The ratio $${{{{\lambda _p}} \over {{\lambda _\alpha }}}}$$ is :
A
8
B
2.8
C
7.8
D
3.8
2
JEE Main 2021 (Online) 24th February Evening Slot
+4
-1
An X-ray tube is operated at 1.24 million volt. The shortest wavelength of the produced photon will be :
A
10$$-$$2 nm
B
10$$-$$1 nm
C
10$$-$$3 nm
D
10$$-$$4 nm
3
JEE Main 2021 (Online) 24th February Evening Slot
+4
-1
Match List - I with List - II.

List I List II
(a) Source of microwave frequency (i) Radioactive decay of nucleus
(b) Source of infrared frequency (ii) Magnetron
(c) Source of Gamma Rays (iii) Inner shell electrons
(d) Source of X-rays (iv) Vibration of atoms and molecules
(v) LASER
(vi) RC circuit

Choose the correct answer from the options given below :
A
(a)-(vi), (b)-(v), (c)-(i), (d)-(iv)
B
(a)-(ii), (b)-(iv), (c)-(i), (d)-(iii)
C
(a)-(ii), (b)-(iv), (c)-(vi), (d)-(iii)
D
(a)-(vi), (b)-(iv), (c)-(i), (d)-(v)
4
JEE Main 2021 (Online) 24th February Evening Slot
+4
-1
According to Bohr atom model, in which of the following transitions will the frequency be maximum?
A
n = 2 to n = 1
B
n = 3 to n = 2
C
n = 4 to n = 3
D
n = 5 to n = 4
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