NEET Modern Physics MCQs & PYQs

Consider the following nuclear reactions and select the correct statements from the options that
follow.

(A) Free neutron has higher mass than proton, therefore reaction I is possible
(B) Free proton has less mass than neutron, therefore reaction II is not possible for the free
proton
(C) Inside a nucleus, both decays (reaction I and II) are possible
(D) Inside a nucleus, reaction I is not possible but reaction II is possible.

Mark the incorrect statement :

The correct graph between the maximum energy of a photoelectron and the inverse of wavelength of the incident radiation is given by the curve

A photon and an electron have equal energy E. \[\lambda_{photon}/\lambda_{electron}\] is proportional to

Ultraviolet light of wavelength 300 nm and intensity 1.0 watt/m² falls on the surface of a photosensitive material. If 1% of the incident photons produce photoelectrons, then the number of photoelectrons emitted from an area of 1.0 cm² of the surface is nearly

A photon of wavelength 6630 Å is incident on a totally reflecting surface. The momentum delivered by the photon is equal to

Photoelectric emission is observed from a metallic surface for frequencies ν1 and ν2 of the incident light rays (ν1 > ν2). If the maximum value of kinetic energy of the photoelectrons emitted in the two cases are in the ratio of 1 : k, then the threshold frequency of the metallic surface is :

The ratio of de-Broglie wavelengths of molecules of hydrogen and helium which are at temperature 27°C and 127° respectively is :

What is energy released in the β-decay of \[^{32}P\longrightarrow ^{32}S\] ?

\[\left( Given:atomic masses:-31.97391amu for ^{32}P and 31.97207amu for ^{32}S \right)\]

The figure shows the variation of photo current with anode potential for a photo-sensitive surface for three different radiations. Let Ia, Ib, and Ic be the intensities and fa, fb and fc be the frequencies for the curves a, b and c respectively :