1
JEE Main 2021 (Online) 24th February Evening Shift
+4
-1
According to Bohr's atomic theory :

(A) Kinetic energy of electron is $$\propto {{{Z^2}} \over {{n^2}}}$$.

(B) The product of velocity (v) of electron and principal quantum number (n), $$'vn' \propto {Z^2}$$.

(C) Frequency of revolution of electron in an orbit is $$\propto {{{Z^3}} \over {{n^3}}}$$.

(D) Coulombic force of attraction on the electron is $$\propto {{{Z^3}} \over {{n^4}}}$$.

Choose the most appropriate answer from the options given below :
A
(A), (C) and (D) only
B
(A) only
C
(C) only
D
(A) and (D) only
2
JEE Main 2020 (Online) 5th September Evening Slot
+4
-1
The correct statement about probability density (except at infinite distance from nucleus) is :
A
It can be zero for 1s orbital
B
It can be zero for 3p orbital
C
It can never be zero for 2s orbital
D
It can negative for 2p orbital
3
JEE Main 2020 (Online) 5th September Morning Slot
+4
-1
The difference between the radii of 3rd and 4th
orbits of Li2+ is R1 . The difference between the
radii of 3rd and 4th orbits of He+ is $$\Delta$$R2 .
Ratio $$\Delta$$R1 : $$\Delta$$R2 is :
A
8 : 3
B
3 : 2
C
2 : 3
D
3 : 8
4
JEE Main 2020 (Online) 4th September Evening Slot
+4
-1
The shortest wavelength of H atom in the Lyman series is $$\lambda$$1. The longest wavelength in the Balmar series of He+ is :
A
$${{5{\lambda _1}} \over 9}$$
B
$${{36{\lambda _1}} \over 5}$$
C
$${{27{\lambda _1}} \over 5}$$
D
$${{9{\lambda _1}} \over 5}$$
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