Pls use C S Toh's guide book with caution. It is barely enough
to get you a high B. It is an outdated book which needs
updating.
It was written for the 2007 chem syllabus, which was not as
demanding as the 2010-2014 syllabus.
Even some neighbourhood JC's lecture notes are insufficient for
2013- 2014 syllabus,as examiners used concepts and questions from
first year university textbooks in 2010-2012 exam papers.
The bar has been raised.
To secure a good A grade, you need to read organic chemistry
university textbooks.