1
JEE Main 2019 (Online) 8th April Evening Slot
MCQ (Single Correct Answer)
+4
-1
If p is the momentum of the fastest electron ejected from a metal surface after the irradiation of light having wavelength $$\lambda $$, then for 1.5 p momentum of the photoelectron, the wavelength of the light should be: (Assume kinetic energy of ejected photoelectron to be very high in comparison to work function)
A
1/2 $$\lambda $$
B
3/4 $$\lambda $$
C
4/9 $$\lambda $$
D
2/3 $$\lambda $$
2
JEE Main 2019 (Online) 8th April Morning Slot
MCQ (Single Correct Answer)
+4
-1
The quantum number of four electrons are given below :
n = 4, l = 2, ml =–2, ms = –1/2
n = 3, l = 2, ml = 1, ms = +1/2
n = 4, l = 1, ml = 0, ms = +1/2
n = 3, l = 1, ml = 1, ms = –1/2
The correct order of their increasing enegies will be :
A
IV < II < III < I
B
I < III < II < IV
C
IV < III < II < I
D
I < II < III < IV
3
JEE Main 2019 (Online) 12th January Evening Slot
MCQ (Single Correct Answer)
+4
-1
If the de Broglie wavelength of the electron in nth Bohr orbit in a hydrogenic atom is equal to 1.5 $$\pi $$a0 (a0 is Bohr radius), then the value of n/z is -
A
0.75
B
0.40
C
1.50
D
1.0
4
JEE Main 2019 (Online) 12th January Evening Slot
MCQ (Single Correct Answer)
+4
-1
The upper stratosphere consisting of the ozone layer protects us from sun's radiation that falls in the wavelength region of -
A
200-315 nm
B
400-550 nm
C
0.8-1.5 nm
D
600-750 nm
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