Number of molecules of water of crystallization in copper sulphate, so

Number of molecules of water of crystallization in copper sulphate, sodium carbonate and Gypsum are

5, 10 and 2 respectively
10, 2 and 5 respectively
5, 2 and 10 respectively
2, 5 and 10 respectively
This question was previously asked in
UPSC NDA-2 – 2020
The correct answer is (A) 5, 10 and 2 respectively.
The number of molecules of water of crystallization are specific to the hydrated forms of these compounds:
– Copper sulphate exists commonly as copper(II) sulphate pentahydrate, CuSO4·5H2O, which has 5 molecules of water.
– Sodium carbonate exists commonly as sodium carbonate decahydrate (washing soda), Na2CO3·10H2O, which has 10 molecules of water.
– Gypsum is calcium sulphate dihydrate, CaSO4·2H2O, which has 2 molecules of water.
Water of crystallization refers to water molecules that are chemically bonded to ions in the crystal structure of a salt. These water molecules are part of the crystalline structure but can be removed by heating the salt.