URGENT NEED HELP QUICKLY can someone answer 4, 5 and 6 pretty please

The ionic compound aluminium sulphate, Al2(SO4)3, is used in the treatment of water to render it suitable for human use. Write an equation for the dissociation of aluminium sulphate in aqueous solution and hence calculate the molar concentration of each ion in a solution of 0.137moldm3 aluminium sulphate. (5 marks) Question 5 (a) Give the full ionic equation and the net ionic equation for the following precipitation reaction, and identify the spectator ions. BaCl2(aq)+2AgNO3(aq)Ba(NO3)2(aq)+2AgCl(s) (4 marks) (b) 2.00dm3 of 3.00moldm3AgNO3 was mixed with 3.00dm3 of 1.00moldm3BaCl2. Show that neither of the reactants is in excess. (3 marks) (c) Calculate the concentration of each ion in aqueous solution after mixing. (3 marks) Question 6 25.0cm3 of a solution of H2SO4 was titrated with 0.210moldm3NaOH.19.5cm3 of the NaOH solution was required to neutralise the H2SO4. Write a balanced equation for the reaction and calculate the concentration of the H2SO4 solution