You can find such diagrams by Googling "four stroke engine" or "Otto cycle" and asking for "images".
An example of what you will find is:
http://images.google.com/imgres?imgurl=http://www.antonine-education.co.uk/Physics_A2/options/Module_7/Topic_4/Otto.jpg&imgrefurl=http://www.antonine-education.co.uk/Physics_A2/options/Module_7/Topic_4/internal_combustion_engines.htm&usg=__-kJK_WVYwaIXSBfPllK1CJVzw_w=&h=380&w=576&sz=43&hl=en&start=4&tbnid=hEOqoJcSgs46PM:&tbnh=88&tbnw=134&prev=/images%3Fq%3D%2522otto%2Bcycle%2522%26gbv%3D2%26hl%3Den%26sa%3DG%26ie%3DUTF-8
diagram the motion of pistons in a four stroke engine.
2 answers
A sample of compound AB decomposes to 48 g of A and 12 g of B. Another sample of the same compound AB decomposes to 24 g of A. Predict the number of grams of B obtained.