If half life of radium is 77 days. Its decay constant in day will be
(a) $3×{10}^{-13}$/day            (b) $9×{10}^{-3}$/day
(c) $1×{10}^{-3}$/day              (d) $6×{10}^{-3}$/day

Concept Questions :-

High Yielding Test Series + Question Bank - NEET 2020

Difficulty Level:

In a sample of radioactive material, what fraction of the initial number of active nuclei will remain undisintegrated after half of a half-life of the sample
(a) $\frac{1}{4}$        (b) $\frac{1}{2\sqrt{2}}$
(c) $\frac{1}{\sqrt{2}}$     (d) $2\sqrt{2}$

Concept Questions :-

High Yielding Test Series + Question Bank - NEET 2020

Difficulty Level:

Consider two nuclei of the same radioactive nuclide. One of the nuclei was created in a supernova explosion 5 billion years ago. The other was created in a nuclear reactor 5 minutes ago. The probability of decay during the next time is
(a) Different for each nuclei
(b) Nuclei created in explosion decays first
(c) Nuclei created in the reactor decays first
(d) Independent of the time of creation

Concept Questions :-

Nuclear reactor

Difficulty Level:

An $\mathrm{\alpha }$-particle of 5 MeV energy strikes with a nucleus of uranium at stationary at an scattering angle of 180o. The nearest distance upto which $\mathrm{\alpha }$-particle reaches the nucleus will be of the order of
(a) 1 Å               (b)
(c)       (d)

Concept Questions :-

Types of decay
High Yielding Test Series + Question Bank - NEET 2020

Difficulty Level:

In a hypothetical Bohr hydrogen, the mass of the electron is doubled. The energy ${\mathrm{E}}_{0}$ and the radius ${\mathrm{r}}_{0}$ of the first orbit will be (${\mathrm{a}}_{0}$ is the Bohr radius)
(a)
(b)
(c)
(d)

High Yielding Test Series + Question Bank - NEET 2020

Difficulty Level:

A double charged lithium atom is equivalent to hydrogen whose atomic number is 3. The wavelength of required radiation for exciting electron from first to third Bohr orbit in ${\mathrm{Li}}^{++}$ will be (Ionisation energy of hydrogen atom is 13.6eV)
(a) 182.51 Å                 (b) 177.17 Å
(c) 142.25 Å                 (d) 113.74 Å

High Yielding Test Series + Question Bank - NEET 2020

Difficulty Level:

The ionisation potential of H-atom is  13.6 V. When it is excited from ground state by monochromatic radiations of , the number of emission lines will be (according to Bohr’s theory)
(a) 10            (b) 8
(c) 6              (d) 4

High Yielding Test Series + Question Bank - NEET 2020

Difficulty Level:

A neutron with velocity V strikes a stationary deuterium atom. Its kinetic energy changes by a factor of
(a) $\frac{15}{16}$              (b) $\frac{1}{2}$
(c) $\frac{2}{1}$                (d) None of these

Concept Questions :-

Mass-energy equivalent
High Yielding Test Series + Question Bank - NEET 2020

Difficulty Level:

The sun radiates energy in all directions. The average radiations received on the earth surface from the sun is 1.4 $\mathrm{kilowatt}/{\mathrm{m}}^{2}$.The average earth- sun distance is $1.5×{10}^{11}$ metres. The mass lost by the sun per day is
(1 day = 86400 seconds)
(a)           (b)
(c)          (d)

Concept Questions :-

Mass-energy equivalent
High Yielding Test Series + Question Bank - NEET 2020

Difficulty Level:

The binding energy per nucleon of ${\mathrm{O}}^{16}$ is 7.97 MeV and that of ${\mathrm{O}}^{17}$ is 7.75 MeV. The energy (in MeV) required to remove a neutron from ${\mathrm{O}}^{17}$ is
(a) 3.52                 (b) 3.64
(c) 4.23                 (d) 7.86

Concept Questions :-

Nuclear binding energy