Density is mass over volume
Density = 106g/23cm³ = 4.6g/cm³
<span>The expected results of the Rutherford's gold foil experiment were that the relative massive alpha particles (respect to electrons) could go through the gold foil without being deviated of their trajectory or only small deviations due to the uniformly distributed positive charge of the protons. The real results showed that some particles were significantly deviated of the trajectory (large deviation angles and even some particles bounced back to the source). This lead Rutherford to reject the plum pudding model and propose a new one. The new model proposed by Rutherford was that the atom consisted of a small and every dense nucleus (which contained the positive charge, protons) and a vast region, almost empty, but where the electrons were, surrounding the nucleus.</span><span />
Answer: (E) 300 bq
Explanation:
Half life is the amount of time taken by a radioactive material to decay to half of its original value.
Radioactive decay process is a type of process in which a less stable nuclei decomposes to a stable nuclei by releasing some radiations or particles like alpha, beta particles or gamma-radiations. The radioactive decay follows first order kinetics.
Half life is represented by 
Half life of Thallium-208 = 3.053 min
Thus after 9 minutes , three half lives will be passed, after ist half life, the activity would be reduced to half of original i.e. 
, after second half life, the activity would be reduced to half of 1200 i.e. 
, and after third half life, the activity would be reduced to half of 600 i.e. 
,
Thus the activity 9 minutes later is 300 bq.
