JEE Main 2021 (Online) 1st September Evening Shift | Dual Nature of Radiation Question 32 | Physics

JEE Main 2021 (Online) 1st September Evening Shift

MCQ (Single Correct Answer)

-1

The temperature of an ideal gas in 3-dimensions is 300 K. The corresponding de-Broglie wavelength of the electron approximately at 300 K, is :

[m_e = mass of electron = 9 $$\times$$ 10^$$-$$31 kg, h = Planck constant = 6.6 $$\times$$ 6.6 $$\times$$ 10^$$-$$34 Js, k_B = Boltzmann constant = 1.38 $$\times$$ 10^$$-$$23 JK^$$-$$1]

6.26 nm

8.46 nm

2.26 nm

3.25 nm

JEE Main 2021 (Online) 1st September Evening Shift

MCQ (Single Correct Answer)

-1

The half life period of radioactive element x is same as the mean life time of another radioactive element y. Initially they have the same number of atoms. Then :

x-will decay faster than y.

y-will decay faster than x.

x and y have same decay rate initially and later on different decay rate.

x and y decay at the same rate always.

JEE Main 2021 (Online) 31st August Evening Shift

MCQ (Single Correct Answer)

-1

A free electron of 2.6 eV energy collides with a H⁺ ion. This results in the formation of a hydrogen atom in the first excited state and a photon is released. Find the frequency of the emitted photon. (h = 6.6 $$\times$$ 10^$$-$$34 Js)

1.45 $$\times$$ 10¹⁶ MHz

0.19 $$\times$$ 10¹⁵ MHz

1.45 $$\times$$ 10⁹ MHz

9.0 $$\times$$ 10²⁷ MHz

JEE Main 2021 (Online) 31st August Evening Shift

MCQ (Single Correct Answer)

-1

Consider two separate ideal gases of electrons and protons having same number of particles. The temperature of both the gases are same. The ratio of the uncertainty in determining the position of an electron to that of a proton is proportional to :-

$${\left( {{{{m_p}} \over {{m_e}}}} \right)^{3/2}}$$

$$\sqrt {{{{m_e}} \over {{m_p}}}} $$

$$\sqrt {{{{m_p}} \over {{m_e}}}} $$

$${{{m_p}} \over {{m_e}}}$$

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