1
BITSAT 2023
MCQ (Single Correct Answer)
+3
-1

The total energy of an electron in the second excited state of hydrogen atom is about $$-1.51 \mathrm{~eV}$$. Its kinetic energy in this state is

A
$$-1.5 \mathrm{~eV}$$
B
$$-3.02 \mathrm{~eV}$$
C
3.02 eV
D
1.51 eV
2
BITSAT 2023
MCQ (Single Correct Answer)
+3
-1

After two hours one-eight of the starting amount of a certain radioactive isotope remained undecayed. The half-life of the isotope is

A
15 min
B
40 min
C
45 min
D
4 h
3
BITSAT 2022
MCQ (Single Correct Answer)
+3
-1

In a radioactive material the activity at time t1, is A1 and at a later time t2, it is A2. If the decay constant of the material is $$\lambda$$, then

A
$${A_1} = {A_2}\,{e^{ - \lambda ({t_1} - {t_2})}}$$
B
$${A_1} = {A_2}\,{e^{\lambda ({t_1} - {t_2})}}$$
C
$${A_1} = {A_2}({t_2}/{t_1})$$
D
$${A_1} = {A_2}$$
4
BITSAT 2021
MCQ (Single Correct Answer)
+3
-1

A proton has kinetic energy E = 100 eV which is equal to that of a photon. The wavelength of photon is $$\lambda$$2 and that of proton is $$\lambda$$1. The ratio $${{{\lambda _2}} \over {{\lambda _1}}}$$ is proportional to

A
E2
B
E$$^{{1 \over 2}}$$
C
E$$-$$1
D
E$$^{ - {1 \over 2}}$$
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