1
COMEDK 2025 Afternoon Shift
MCQ (Single Correct Answer)
+1
-0
What is the frequency ' $\nu$ ' of the electron in Bohr's first orbit of radius ' $r$ ' of the hydrogen atom?
A
$v=\frac{e^2}{4 \pi \varepsilon_0 h r}$
B
$v=\frac{e^2}{2 \pi \varepsilon_0 h r^2}$
C
$v=\frac{e^2}{4 \pi \varepsilon_0 h r^2}$
D
$v=\frac{e^2}{2 \pi \varepsilon_0 h r}$
2
COMEDK 2025 Afternoon Shift
MCQ (Single Correct Answer)
+1
-0
To get 300 MW electric power for half an hour, how much mass is to be completely converted into energy?
A
$6 \times 10^{-2} \mathrm{~kg}$
B
$3 \times 10^{-6} \mathrm{~kg}$
C
$6 \times 10^{-3} \mathrm{~kg}$
D
$6 \times 10^{-6} \mathrm{~kg}$
3
COMEDK 2025 Afternoon Shift
MCQ (Single Correct Answer)
+1
-0
Fusion reaction is more energetic than fission reaction because
A
Uncontrolled chain reaction is taking place In the fusion reaction.
B
Fusion reaction is taking place at very high temperature
C
The energy released per unit mass of the fuel in fusion reaction is larger than the energy released per unit mass of the fuel in fission reaction.
D
In the fusion reaction lighter nuclei combine to form a heavier nucleus
4
COMEDK 2025 Afternoon Shift
MCQ (Single Correct Answer)
+1
-0
The nucleus of oxygen atom contains 8 protons and 8 neutrons. What is the mass defect in amu? [Given Mass of proton $=1.00727 \mathrm{amu}$ Mass of neutron $=1.00866 \mathrm{amu}$ and the mass of oxygen nucleus $=15.99053 \mathrm{amu}$. ]
A
0.12691 amu
B
0.13692 amu
C
0.13691 amu
D
0.12961 amu
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