1
JEE Main 2021 (Online) 18th March Morning Shift
MCQ (Single Correct Answer)
+4
-1
Out of Syllabus
Change Language
A radioactive sample disintegrates via two independent decay processes having half lives $$T_{1/2}^{(1)}$$ and $$T_{1/2}^{(2)}$$ respectively. The effective half-life T1/2 of the nuclei is :
A
None of the above
B
$${T_{1/2}} = T_{1/2}^{(1)} + T_{1/2}^{(2)}$$
C
$${T_{1/2}} = {{T_{1/2}^{(1)}T_{1/2}^{(2)}} \over {T_{1/2}^{(1)} + T_{1/2}^{(2)}}}$$
D
$${T_{1/2}} = {{T_{1/2}^{(1)} + T_{1/2}^{(2)}} \over {T_{1/2}^{(1)} - T_{1/2}^{(2)}}}$$
2
JEE Main 2021 (Online) 17th March Evening Shift
MCQ (Single Correct Answer)
+4
-1
Change Language
The atomic hydrogen emits a line spectrum consisting of various series. Which series of hydrogen atomic spectra is lying in the visible region?
A
Brackett series
B
Balmer series
C
Paschen series
D
Lyman series
3
JEE Main 2021 (Online) 17th March Morning Shift
MCQ (Single Correct Answer)
+4
-1
Change Language
If an electron is moving in the nth orbit of the hydrogen atom, then its velocity (vn) for the nth orbit is given as :
A
$${v_n} \propto {1 \over n}$$
B
vn $$ \propto $$ n2
C
vn $$ \propto $$ n
D
$${v_n} \propto {1 \over {{n^2}}}$$
4
JEE Main 2021 (Online) 17th March Morning Shift
MCQ (Single Correct Answer)
+4
-1
Change Language
Which level of the single ionized carbon has the same energy as the ground state energy of hydrogen atom?
A
8
B
6
C
1
D
4
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