please answer a b and c as briefly as possible

An unknown gas, D, reacts with fluorine gas to form the compound DF4(9), as represented by the following equation, D(g) +2F%(9) DF4(9) A series of experimental trials were performed at 600C to determine the rate law expression for the reaction. Data from the trials are shown below Initial Pb Initial P., Initial Rate of Appearance of DF (9) (torr/min) (torr) (torr) Trial 1 3000 3000 Trial 2 6000 3000 2.50 x 10-2 5.00 x 102 10.0 X 102 Trial 3 3000 6000 (a) A student claims that the reaction is second order with respect to D(9). Do you agree or disagree? Justify your answer using the data above (b) What is the initial rate of disappearance of F2(9) in trial 27 Justify your answer (C) A student claims that if element Dis in group 16, then the molecular geometry of DF (9) is tetrahedral. Do you agree or disagree with the student? Justify your answer in terms of VSEPR theory