3. (a) Transition metals and group 1 metals have many properties in common because they are all metals - Edexcel - GCSE Chemistry - Question 3 - 2019 - Paper 1

1. The magnesium metal will gradually dissolve, and you would observe the disappearance of the magnesium ribbon in the solution.
2. The color of the solution will change from colorless to blue as copper ions are formed and copper metal precipitates from the solution.

The other substance needed for iron to rust is oxygen.

1. Clean two iron nails to ensure there is no pre-existing rust.
2. Place one nail in a test tube filled with freshwater and the other in a test tube filled with seawater.
3. Leave both test tubes for a period of time, such as one week.
4. Observe the nails and record any changes, comparing the rusting and appearance of both nails.

To calculate the mass of zinc required, use the formula:

$ext{Mass} = ext{Surface Area} imes ext{Zinc layer thickness}$

Substituting in the values:

$ext{Mass} = 0.68 ext{ m}^2 imes 200 ext{ g m}^-2 = 136 ext{ g}$

Thus, the mass of zinc required is 136 g.