Part (a) was well attempted.  However, many of the candidates drew the expected diagram carelessly and so lost valuable marks.  One such example is given below:

Part (b) was fairly well attempted.
Part (c) was well attempted by the responding candidates.

The expected answers are:
(a)      (i)          (A)       gamma rays → beta rays →  alpha particles.             

                        (B)       alpha particles → beta rays → gamma rays.     
              
            Accept:    γ → β →  α   and
                            α → β  → γ
       (ii)

β ray is strongly deflected  (because it is negatively charged.                                    

1. α particle is deflected but not as strong as the  β  - beta (because it is massive)
2. γ rays is not affected (because it has neither  charge nor mass).                     

 (i)  -     The energy/frequency of incident radiation must be greater than thework function/threshold frequency of the metal       
(ii)  -   the intensity of the radiation 
(iii)- Energy/frequency of incident radiation/ work function of the metal irradiated    
         
     (c)  E = hf                                                                                                                    
=  6.6 x 10-34 x 5.02 x 1014                                                                                  

=  3.31  x 10-19 J 
1 e V = 1.6 X 10-19 J
∴  3.31 x 10-19 J  =  2.07  e V