Can u give me some imp. problems from atmic structure.

2)mass of 2 curie uranium(234)is_______

3)Half life of radium is 1620yrs &its atomic weight =226kg/kilomole.No. of atoms that will decay from 1 gm. of sample per second will be _________

4)Ratio of momenta of an electron of mass m_e and an alpha particle of mass m_a which are accelerated from rest by a potential difference of 250V is_______