Simple recall questions are usually worth one mark. They often have command words like 'Give', 'State', 'Name' or 'Identify'. Some questions may ask you to state two things, rather than just one, and will be worth two marks.
Structured questions, with command words such as 'Describe' or 'Explain', will be worth two or more marks:
More complex structured questions will be worth three to five marks. They include questions with complex descriptions and explanations, questions in which you need to compare and contrast two different things, or calculations with several stages.
The mark schemes given here may show answers as bullet points. This is to show clearly how a mark can be obtained. However, it is important that your answer is written in a logical, linked way.
These questions have been written by Bitesize consultants as suggestions to the types of questions that may appear in an exam paper.
Butane gas is usually used for refuelling lighters and can be bought in canisters.
a) Explain why it is known as butane gas, even though it is stored as a liquid inside the canister. [3 marks]
b) Why should a butane gas canister not be stored at temperatures above 50°C? [2 marks]
a) The butane inside the canister is under a large pressure. This means that the butane particles are pushed very close together so that they change from the gas to the liquid state. When the butane is released from the can into the atmosphere, the pressure drops and it changes from liquid to gas.
b) At higher temperatures the butane particles will move quicker and the pressure will increase inside the can dramatically. This could rip open the canister and release a large amount of butane in one go which could be dangerous if it ignites.
A bicycle pump is sealed at one end and the piston pushed until the pressure of the air inside increases to 3 × 105 Pa.
a) The person pushing the pump notices that it heats up slightly on doing this. Why does this happen? [1 mark]
b) Explain in terms of particles why the air pressure increases inside the pump. [2 marks]
The area of the piston compressing the air is 4 × 10−4 m2.
c) Calculate the force of the trapped air on the piston by using an equation you can recall. [3 marks]
a) Work is done on the gas that transforms into an increase in internal energy, hence a rise in temperature.
b) The fast moving gas particles have less space to move. They will therefore collide more often with the walls of the pump. The means more force on the walls and less area to collide with, resulting in a greater pressure.
c) Pressure = force ÷ area
Force = pressure × area = 3 × 105 × 4 × 10-4 = 12 × 101 = 1.2 × 102 N or 120 N.