2.40g of copper (ii)tetraoxosulphate(iv) crystals are prepared from 0.45g of copper (ii) oxide.the copper (ii) tetraoxosulphate(vi) crystals contain 0.45g of water of crystallisation.what mass of crystals and what is the mass of water of crystallisation would be obtained from 1.2g of copper (ii) oxide.

2 answers

The proper name for CuSO4 is copper(II) sulfate and that nutty name you've given it is out in left field somewhere.
You could go through the obvious stoichiometry steps but this isn't necessary in this problem if you recognize that this is a proportion.
0.45 g CuO produces 2.40 g CuSO4.xH2O with 0.45 g H2O so
1.20 g CuO produces.....x g CuSO4 with .....x g H2O

2.40 g CuSO4.xH2O x (1.20/0.45 = ? grams of the crystals.
0.45 g H2O x (1.20/0.45) = ? grams H2O in the crystals.
What is copper (ii) tetraoxsuiphater (vi)