Question 1 (25 marks): Answer each of the following (18 marks): (a) Potassium chloride (KCI) reacts with sodium dichromate (Na Cr,O,) in water under acidic conditions according to the following (unbalanced) redox reaction: Cr + Cr,0,2 Cl + Cm ) Assign the oxidation number to each element and clearly identify the chemical species that are oxidized and reduced. Justify your statements. [1 mark] (ii) Write down the balanced half-reactions. Show workings. [4 marks) (iii) Balance the overall redox reaction. Show workings. [3 marks) (b) With reference to the molecule of sulfur tetrafluoride (SF.): (i) Determine the oxidation number of each element. [1 mark] (ii) Draw and justify its Lewis structure. [3 marks] (iii) Calculate the formal charge for each atom. [1 mark] (iv) Use the VSEPR model to predict the molecular geometry, the F-S-F angles and the polarity of the molecule. Justify your statements. (5 marks) Answer either (c) or (d) (7 marks).