Nuclei

The binding energy per nucleon of ¹⁶O is 7.97 MeV and that of ¹⁷O is 7.75 MeV. The energy in MeV required to remove a neutron from ¹⁷O is

• 3.52 

• 3.64

• 4.23

• 7.86

If the ratio of the radius of a nucleus with 61 neutrons to that of helium nucleus is 3, then the atomic number of this nucleus is

• 27

• 47

• 51

• 61

A radioactive sample contains 10^-3 kg each of two nuclear species A and B with half-life 4 days and 8 days, respectively. The ratio of the amounts of A and B after period of 16 days is

• 1 : 2

• 4 : 1

• 1 : 4

• 2 : 1

The binding energy per nucleon for deuteron (₁H²) and helium (₂He⁴) are 1.1 MeV and 7 .0 MeV, respectively. The energy released when two deuterons fuse to form a helium nucleus is

• 36.2 MeV

• 23.6 MeV

• 47.2 MeV

• 11.8 MeV

In a series of radioactive decays, if a nucleus of mass number 180 and atomic number 72 decays into another nucleus of mass number 172 and atomic number 69, then the number of α and β particles released respectively are

• 2,3

• 2,2

• 2,1

• 2,0

The half-life of a radioactive substance is 20 min. The time  taken between 50 % decay and 87.5 % decay of the substance will be

• 20 min

• 30 min

• 40 min

• 25 min

The ratio of the surface area of the nuclei ₅₂Te¹²⁵ to that of ₁₃Al¹²⁷ is 

• $\frac{5}{3}$

• $\frac{125}{17}$

• $\frac{1}{4}$

• $\frac{25}{9}$

On an average, the number of neutrons and the energy of a neutron released per fission of a uranium atom are respectively

• 2.5 and 2 keV

• 3 and 1 keV

• 2.5 and 2 MeV

• 2 and 2 keV

A radioactive material of half-life time of 69.3 days kept in a container. $\frac{2}{3} \mathrm{rd}$ of the substance remains undecayed after (given, $\ln \frac{3}{2} = 0.4$)

• 20 days

• 25 days

• 35 days

• 40 days

The ratio between the radii of nuclei with mass numbers 27 and 125 is

• 5 : 3

• 3 : 5

• 27 : 125

• 125 : 27