Q4 a) What are the two methods of stabilising a particle sol? Your answer should include diagrams and equations where appropriate. (6 marks) b) What are the two essential ingredients needed for a typical sol-gel synthesis? Give examples where appropriate. (2 marks) c) What are the two reactions that occur when the two essential reagents are mixed and describe the resulting product? Your answer should include equations where necessary. (6 marks) d) Describe how a sol can evolve into a gel over time. Use diagrams where appropriate. (3 marks) e) Giving your reasons, which microscopy technique would you use and how would you prepare the sample in order to investigate the following: i. The interface of a silica sol-gel coating 100nm thick with its aluminium substrate. ii. The size cadmium selenide quantum dots 15nm in diameter dispersed as part of a sol. (8 marks)