JEE Main 2020 (Online) 7th January Morning Slot | Atoms and Nuclei Question 193 | Physics

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

Consider an electron in a hydrogen atom revolving in its second excited state (having radius 4.65 $$\mathop A\limits^o $$). The de-Broglie wavelength of this electron is :

6.6 $$\mathop A\limits^o $$

3.5 $$\mathop A\limits^o $$

9.7 $$\mathop A\limits^o $$

12.9 $$\mathop A\limits^o $$

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

Out of Syllabus

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

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