Question

1. how might the final traces (small amounts) of water be removed from your sand samples to ensure that they are totally dry?
2. give two reasons why the sand you have obtained might still be contaminated with salt

Explanation:

For question 5, one way to remove small - amounts of water from sand samples to ensure they are dry is by heating the sand gently in an oven at a low temperature. This evaporates the water. Another method is to place the sand in a desiccator with a desiccant like silica gel which absorbs the water.
For question 6, one reason the sand might still be contaminated with salt is if the washing process to remove salt was incomplete, for example, not enough water was used to dissolve and wash away all the salt. Another reason could be that during the drying process, some salt - containing water droplets might have re - deposited salt on the sand as the water evaporated.

Answer:

1. Heat gently in an oven or use a desiccator with desiccant.
2. Incomplete washing; Re - deposition during drying.