1
JEE Main 2019 (Online) 8th April Morning Slot
+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
2
JEE Main 2019 (Online) 12th January Evening Slot
+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
3
JEE Main 2019 (Online) 12th January Evening Slot
+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
4
JEE Main 2019 (Online) 12th January Morning Slot
+4
-1
What is the work function of the metal if the light of wavelength 4000$$\mathop A\limits^ \circ$$ generates photoelectrons of velocity 6 $$\times$$ 105 ms–1 from it ?
(Mass of electron = 9 $$\times$$ 10–31 kg;
Velocity of light = 3 $$\times$$ 108 ms$$-$$1
Plank's constant = 6.626 $$\times$$ 10–34 Js;
Charge of electron = 1.6 $$\times$$10–19 JeV–1)
A
4.0 eV
B
0.9 eV
C
2.1 eV
D
3.1 eV
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