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

A radioactive element  ${}_{90}\mathrm{X}^{238}$ decays into ${}_{83}\mathrm{Y}^{ 222}$. The number of β-particles emitted are 

• 1

• 2

• 4

• 6

The binding energy per nucleon is maximum in the case

• ${}_{92}{}^{235}\mathrm{U}$

• ${}_{56}{}^{141}\mathrm{Ba}$

• ${}_{26}{}^{56}\mathrm{Fe}$

• ${}_4{}^2\mathrm{He}$

The half-life of radio isotope is 4 h. 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

Remaining quantity (in%) of radioactive element after 5 half lives is

• 4.125%

• 3.125%

• 31.1%

• 42.125%

The half-life of ¹⁹⁸Au is 2.7 days. The average life is

• 4 days

• 3.4 days

• 3.9 days

• None of the above

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 c²

• ( M_O - 17M_n ) c²

• (M_O - 8M_p ) c²

• ( 8 M_p + 9 M_n - M_O)