Clean, dry air is a mixture of several different gases.
Which gas makes up the largest proportion of clean, dry air by volume?
A Argon B Carbon dioxide C Nitrogen D Oxygen
The diagram below shows a laboratory set-up for evaporation, which is part of the crystallisation process used to obtain pure crystals of copper(II) sulfate from a solution.
These sentences describe the steps in the experimental method for carrying out this crystallisation, but they are in the wrong order.
Put a letter in each box to show the correct order of the steps. One has been done for you.
Q \begin{array}{|c|c|c|c|c|} \hline \quad & \quad & \text{Q} & \quad & \quad \\ \hline \end{array} Q
