1
COMEDK 2024 Evening Shift
MCQ (Single Correct Answer)
+1
-0

If an electron in a hydrogen atom jumps from the third orbit to the second orbit, it emits a photon of wavelength $$\lambda$$. When it jumps from the second to the first orbit, the corresponding wavelength of the photon will be

A
$$ \frac{5 \lambda}{27} $$
B
$$ \frac{7 \lambda}{20} $$
C
$$ \frac{16 \lambda}{9} $$
D
$$ \frac{20 \lambda}{7} $$
2
COMEDK 2024 Evening Shift
MCQ (Single Correct Answer)
+1
-0

An electron has a mass of $$9.1 \times 10^{-31} \mathrm{~kg}$$. It revolves round the nucleus in a circular orbit of radius $$0.529 \times 10^{-10} \mathrm{~m}$$ at a speed of $$2.2 \times 10^6 \mathrm{~ms}^{-1}$$. The magnitude of its angular momentum is

A
$$1.06 \times 10^{-34} \mathrm{Kg} \mathrm{m}^2 \mathrm{~s}^{-1}$$
B
$$1.06 \times 10^{-24} \mathrm{Kg} \mathrm{m}^2 \mathrm{~s}^{-1}$$
C
$$2.06 \times 10^{-34} \mathrm{Kg} \mathrm{m}^2 \mathrm{~s}^{-1}$$
D
$$2.06 \times 10^{-24} \mathrm{Kg} \mathrm{m}^2 \mathrm{~s}^{-1}$$
3
COMEDK 2024 Evening Shift
MCQ (Single Correct Answer)
+1
-0

$$ \text { If the nuclear radius of }{ }^{27} \mathrm{Al} \text { is } 3.6 \text { fermi, the nuclear radius of }{ }^{125} \mathrm{Fe} \text { is } $$

A
$$6 \times 10^{-10} \mathrm{~m}$$
B
$$6 \times 10^{-13} \mathrm{~m}$$
C
$$6 \times 10^{-15} \mathrm{~m}$$
D
$$6 \times 10^{-12} \mathrm{~m}$$
4
COMEDK 2024 Morning Shift
MCQ (Single Correct Answer)
+1
-0

The ratio of the radii of the nucleus of two element $$\mathrm{X}$$ and $$\mathrm{Y}$$ having the mass numbers 232 and 29 is:

A
4 : 1
B
1 : 4
C
1 : 2
D
2 : 1
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