The scientist who is credited with discovery of 'nucleus' in an atom is

• Rutherford

• Niels Bohr

• Balmer

• J J Thomson

In nuclear fission the percentage of mass converted into energy is about

• 0.01 %

• 10 %

• 1 %

• 0.1 %

The SI unit of radioactivity is

• Rutherford

• Roentgen

• Becqueral

• Curie

In a sample of radioactive material, what percentage of the initial number of active nuclei will decay during one mean life ?

• 63 %

• 69.3 %

• 37 %

• 50 %

If radius of the  nucleus is taken to be R_Al, then the radius of  nucleus is nearly

When an alpha particle of mass m moving with velocity v bombards on a heavy nucleus of charge Ze, its distance of closest approach from the nucleus depends on mass as,

• 
• 

• m

• m

The half-life to a radioactive nucleus is 50 days. The time interval (t₂-t₁) between the time t₂ when 2/3 of  it has decayed and the time t₁ when 1/3 of it had decayed is

• 30 days

• 50 days

• 60 days

• 15 days

If the nuclear radius of²⁷ Al is 3.6 Fermi, the approximate nuclear radius of ⁶⁴Cu in Fermi is

• 2.4

• 1.2

• 4.8

• 4.8

129.

A mixture consists of two radioactive materials A₁ and A₂ with half-lives of 20 s and 10 s respectively. Initially, the mixture has 40 g of A₁ and 160 g of A₂. The amount of the two in the mixture will become equal after

• 60 s

• 80 s

• 20 s

• 20 s

The binding energy per nucleon of  nuclei are 5.60 MeV and 7.06 MeV, respectively. In the nuclear reaction, , the value of energy Q released is,

• 19.6 MeV

• -2.4 MeV

• 8.4 MeV

• 8.4 MeV