RAM of copper (II) tetraoxosulphate (VI) pentahydrate.

The molar mass of copper (II) tetraoxosulphate (VI) pentahydrate can be calculated as follows:

Copper (II) tetraoxosulphate (VI):
- Copper (II) ion (Cu2+): 1 x 63.55 g/mol = 63.55 g/mol
- Tetraoxosulphate (VI) ion (SO4^2-): 1 x 96.06 g/mol = 96.06 g/mol

Pentahydrate:
- Water (H2O): 5 x 18.02 g/mol = 90.1 g/mol

Combining the above components, the molar mass of copper (II) tetraoxosulphate (VI) pentahydrate is:
Molar mass = 63.55 + 96.06 + 90.1 = 249.71 g/mol

Therefore, the RAM of copper (II) tetraoxosulphate (VI) pentahydrate is approximately 249.71 g/mol.

To find the molar mass of copper (II) tetraoxosulphate (VI) pentahydrate (CuSO4 · 5H2O), we need to add up the atomic masses of each element in the compound.

The atomic masses are as follows:
- Copper (Cu) has an atomic mass of 63.55 g/mol.
- Sulfur (S) has an atomic mass of 32.06 g/mol.
- Oxygen (O) has an atomic mass of 16.00 g/mol.
- Hydrogen (H) has an atomic mass of 1.01 g/mol.

There are 4 oxygen atoms and 5 water molecules, so there are:
4 oxygen atoms × 16.00 g/mol = 64.00 g/mol contribution from oxygen,
5 water molecules × (2 hydrogen atoms × 1.01 g/mol + 1 oxygen atom × 16.00 g/mol) = 90.10 g/mol contribution from water.

Now we can calculate the molar mass of the compound:
Copper (Cu): 1 × 63.55 g/mol = 63.55 g/mol
Sulfur (S): 1 × 32.06 g/mol = 32.06 g/mol
Oxygen (O): 4 × 16.00 g/mol = 64.00 g/mol
Hydrogen (H): 10 × 1.01 g/mol = 10.10 g/mol
Water (H2O): 90.10 g/mol

Adding these up, we get:
63.55 g/mol + 32.06 g/mol + 64.00 g/mol + 10.10 g/mol + 90.10 g/mol = 259.81 g/mol

Therefore, the molar mass of copper (II) tetraoxosulphate (VI) pentahydrate is approximately 259.81 g/mol.