51.

If M_o is the mass of an oxygen isotope ₈O¹⁷ , M_P and M_n are the masses of a proton and a neutron, respectively, the nuclear binding energy of the isotope is

• ( M_o - 8 M_P ) c² 

• ( M_o - 8 M_P - 9 M_c ) c²

• M_o C²

• (M_o - 17 M_n ) c²

Hydrogen bomb is based upon

• fission

• fusion

• chemical reaction

• transmutation

The operation of a nuclear reactor is said to be critical, if the multiplication factor (k) has a value

• 1

• 1.5

• 2.1

• 2.5

Half-lives of two radioactive substances A and B are respectively 20 min and 40 min. Initially the samples of A and B have equal number of nuclei. After 80 min the ratio of remaining number of A and B nuclei is

• 1 : 16

• 4 : 1

• 1 : 4

• 1 : 1

The half-life of a radio-isotope is 4h. If initial mass of the isotope was 200 g, then mass remaining after 24 h will be

• 1.042 g

• 2.084 g

• 3.125 g

• 4.167 g

If ₈₂U²³⁸ emits 8 $\mathrm{\alpha }$ - particles and 6 β - particles, then the resulting nucleus is

• ₈₂U²⁰⁶

• ₈₂Pb²⁰⁶

• ₈₂U²¹⁰

• ₈₂U²¹⁴

The specific charge of a proton is 9.6 x 10⁷ C/kg. The specific charge of an alpha particle will be

• 9.6 x10⁷ C/kg

• 19.2 x 10⁷ C/kg

• 4.8 x10⁷ C/kg

• 2.4 x 10⁷ C/kg

Activity of a radioactive sample decreases to (1/3)rd of its original value in 3 days. Then, in 9 days its activity will become

• (1/27) of the original value

• (1/9) of the original value

• (1/18) of the original value

• (1/3) of the original value

If r₁ and r₂ are the radii of the atomic nuclei of mass numbers 64 and 125 respectively, then the ratio ( r₁/ r₂ ) is

• $\frac{64}{125}$

• $\sqrt{\frac{64}{125}}$

• $\frac{5}{4}$

• $\frac{4}{5}$

the ionization energy of Li²⁺ is equal to 

• 9hcR

• 6hcR

• 2hcR

• hcR