Question

write the name and formulae of 3 hydrated salts

Answer 1

(1) Sodium sulfate decahydrate --------- Na2SO4. 10 H2O

(2) Sodium carbonate decahydrate (washing soda )
---- Na2CO3. 10H2O 

Hope it helps you :)

Answer 2

1. CaSO4.½H2O

2. CaSO4.2H2O

3. Na2CO3.10H2O