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JEE Main 2021 (Online) 18th March Morning Shift
+4
-1
A particle is travelling 4 time as fast as an electron. Assuming the ratio of de-Broglie wavelength of a particle to that of electron is 2 : 1, the mass of the particle is :
A
$${1 \over {16}}$$ times the mass of e$$-$$
B
8 times the mass of e$$-$$
C
16 times the mass of e$$-$$
D
$${1 \over {8}}$$ times the mass of e$$-$$
2
JEE Main 2021 (Online) 18th March Morning Shift
+4
-1
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
$${T_{1/2}} = {{T_{1/2}^{(1)} + T_{1/2}^{(2)}} \over {T_{1/2}^{(1)} - T_{1/2}^{(2)}}}$$
3
JEE Main 2021 (Online) 17th March Evening Shift
+4
-1
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
4
JEE Main 2021 (Online) 17th March Morning Shift
$${v_n} \propto {1 \over n}$$
vn $$\propto$$ n2
vn $$\propto$$ n
$${v_n} \propto {1 \over {{n^2}}}$$