Answer
Please see the work below.
Work Step by Step
(a) We know that the required reaction is:
$CaF_2+H_2SO_4\rightarrow 2HF+CaSO_4$
As the oxidation state of all the elements in the reaction is unchanged, the above reaction is not a redox reaction.
(b) As $H_2SO_4$ is a strong oxidizing agent, it will quickly oxidize $Br^- $and $I^-$ to elemental $Br_2$ and $I_2$.
(c) The required reaction is:
$PBr_3+3H_2O\rightarrow 3HBr+H_3PO_3$
