Solution of Ammonium iron(II) sulfate  (NH4)2Fe(SO4)2 6H2O have to be done at the last minute, about ONE hour before the Exam. 

                               !!  ALWAYS GIVE THE HAZCARD !!

Practical with Sodium sulfITE, test with acidified potassium manganate must stay colorless (no reaction with sulfite-sulfate)

Learn Chemistry Enchencing learning and teaching

Finding V1

original concentration X original volume = Desire Consecrations x Desire Final volume

eg: 2m HCl X V1 = 0.1mHCl X 3000ml

c1Xv1=c2Xv2 ---> 2m X V1 = 0.1m X 3000Ml 

2mxV1 = 0.1X 3000

V1 = 0.1x3000 / 2 

v1 = 150ml of Concentrate Hcl to 3000ml

Lead iodide :

will dissolve in hot water from a kettle. You can put some contaminated test tubes in a suitable container (take-away tub) and just pour the hot water water over them. Take out and rinse the test tubes and leave the solution to cool. Once it's recrystallised you can filter it and keep the crystals for disposal. Then add some sodium sulfide (or carbonate) to the filtrate to precipitate out more lead ions, filter and keep the solids, dilute and chuck the solution.