JEE Main 2020 (Online) 7th January Morning Slot | Atoms and Nuclei Question 123 | Physics

JEE Main 2020 (Online) 7th January Morning Slot

MCQ (Single Correct Answer)

-1

The time period of revolution of electron in its ground state orbit in a hydrogen atom is 1.6 $$ \times $$ 10^-16 s. The frequency of revolution of the electron in its first excited state (in s^-1) is :

5.6 $$ \times $$ 10¹²

1.6 $$ \times $$ 10¹⁴

7.8 $$ \times $$ 10¹⁴

6.2 $$ \times $$ 10¹⁵

JEE Main 2019 (Online) 12th April Evening Slot

MCQ (Single Correct Answer)

-1

The electron in a hydrogen atom first jumps from the third excited state to the second excited state and subsequently to the first excited state. The ratio of the respective wavelengths, $${{{\lambda _1}} \over {{\lambda _2}}}$$, of the photons emitted in this process is :

$${{22} \over 5}$$

$${7 \over 5}$$

$${9 \over 7}$$

$${{20} \over 7}$$

JEE Main 2019 (Online) 12th April Evening Slot

MCQ (Single Correct Answer)

-1

Half lives of two radioactive nuclei A and B are 10 minutes and 20 minutes, respectively, If initially a sample has equal number of nuclei, then after 60 minutes, the ratio of decayed numbers of nuclei A and B will be :

9 : 8

1 : 8

8 : 1

3 : 8

JEE Main 2019 (Online) 12th April Morning Slot

MCQ (Single Correct Answer)

-1

An excited He⁺ ion emits two photons in succession, with wavelengths 108.5 nm and 30.4 nm, in making a transition to ground state. The quantum number n, corresponding to its initial excited state is (for photon of wavelength $$\lambda $$, energy $$E = {{1240\,eV} \over {\lambda (in\,nm)}}$$) :

n = 4

n = 7

n = 5

n = 6

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