Six mark questions are extended open response questions. These require longer answers than the structured questions with fewer marks. It is wise to plan your answer rather than rushing straight into it, otherwise you may stray away from the key points.
Six mark questions are marked using a levels-based mark scheme because they are open ended. To gain full marks, you need to:
You are likely to see command words such as:
Six mark questions may be synoptic questions. These questions bring together ideas from two or more topics. For example, a question about atoms could include ideas about atomic structure, isotopes, radiation and nuclear reactions. Remember that the topics covered in the first paper are assumed knowledge for the second paper, so questions in the second paper may need knowledge and understanding of those topics too.
The answers shown here give marking points as bullet points. You do not usually need to include all of them to gain six marks, but you do need to write in full sentences, linking them logically and clearly.
Questions courtesy of Eduqas.
A tree surgeon carries out an experiment on fir trees to find out whether or not they are diseased.
The tree surgeon needs to find the density of an irregular small piece of wood. He uses a method illustrated below to find the density of the piece of wood.
Describe how you would find the density of the wood sample from the information given in the diagrams. [6 marks]
The mass of wood sample is measured = 74.5 - 62.5 = 12 g. 
An object that sinks must be used because wood floats on water. 
The volume of the dense block = 72 - 62 = 10 cm3. 
The volume of wood sample and dense block = 87 - 62 = 25 cm3. 
Therefore the volume of the wood sample = 25 - 10 = 15 cm3 OR the volume of the wood sample = 87 - 72 = 15 cm3. 
Density is calculated by: density = mass ÷ volume = 12 ÷ 15 = 0.8 g/cm3. 
Answering tip: Briefly plan the key points you want to include in your answer. For example:
A gas is held in a syringe. The syringe is prevented from expanding or contracting; it is fixed at constant volume.
Explain in terms of molecular motion and collisions why the pressure changes when the gas is heated. [6 marks]
Molecules in a gas move in random directions and at random speed 
They collide with each other and with the walls 
When a gas is heated molecules move faster 
This means that molecules hit harder  and more often 
Causing the pressure to increase