JEE Main 2021 (Online) 27th August Morning Shift | Atoms and Nuclei Question 70 | Physics

JEE Main 2021 (Online) 27th August Morning Shift

MCQ (Single Correct Answer)

-1

There are 10¹⁰ radioactive nuclei in a given radioactive element, its half-life time is 1 minute. How many nuclei will remain after 30 seconds? $$\left( {\sqrt 2 = 1.414} \right)$$

2 $$\times$$ 10¹⁰

7 $$\times$$ 10⁹

10⁵

4 $$\times$$ 10¹⁰

JEE Main 2021 (Online) 26th August Evening Shift

MCQ (Single Correct Answer)

-1

At time t = 0, a material is composed of two radioactive atoms A and B, where N_A(0) = 2N_B(0). The decay constant of both kind of radioactive atoms is $$\lambda$$. However, A disintegrates to B and B disintegrates to C. Which of the following figures represents the evolution of N_B(t) / N_B(0) with respect to time t?

[N_A (0) = No. of A atoms at t = 0

N_B (0) = No. of B atoms at t = 0]

JEE Main 2021 (Online) 26th August Evening Shift Physics - Atoms and Nuclei Question 71 English Option 1

JEE Main 2021 (Online) 26th August Evening Shift Physics - Atoms and Nuclei Question 71 English Option 2

JEE Main 2021 (Online) 26th August Evening Shift Physics - Atoms and Nuclei Question 71 English Option 3

JEE Main 2021 (Online) 26th August Evening Shift Physics - Atoms and Nuclei Question 71 English Option 4

JEE Main 2021 (Online) 26th August Morning Shift

MCQ (Single Correct Answer)

-1

A particular hydrogen like ion emits radiation of frequency 2.92 $$\times$$ 10¹⁵ Hz when it makes transition from n = 3 to n = 1. The frequency in Hz of radiation emitted in transition from n = 2 to n = 1 will be :

0.44 $$\times$$ 10¹⁵

6.57 $$\times$$ 10¹⁵

4.38 $$\times$$ 10¹⁵

2.46 $$\times$$ 10¹⁵

JEE Main 2021 (Online) 27th July Evening Shift

MCQ (Single Correct Answer)

-1

An electron and proton are separated by a large distance. The electron starts approaching the proton with energy 3 eV. The proton captures the electron and forms a hydrogen atom in second excited state. The resulting photon is incident on a photosensitive metal of threshold wavelength 4000$$\mathop A\limits^o $$. What is the maximum kinetic energy of the emitted photoelectron?

7.61 eV

1.41 eV

3.3 eV

No photoelectron would be emitted

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