Which one of the following statements is correct ?

[amp_mcq option1=”Iron sulphate and copper sulphate crystals have same number of water of crystallization” option2=”Iron sulphate and zinc sulphate crystals have same number of water of crystallization” option3=”Zinc sulphate and copper sulphate crystals have same number of water of crystallization” option4=”Iron sulphate, copper sulphate and zinc sulphate crystals each have same number of water of crystallization” correct=”option2″]

This question was previously asked in

UPSC CAPF – 2015

Download PDF Attempt Online

The statement that is correct is that Iron sulphate and zinc sulphate crystals have the same number of water of crystallization.

Crystals of hydrated salts contain a definite number of water molecules incorporated within their crystal structure. This water is called water of crystallization.
– Iron(II) sulphate (Ferrous sulphate) commonly crystallizes as the heptahydrate, FeSO4.7H2O.
– Copper(II) sulphate commonly crystallizes as the pentahydrate, CuSO4.5H2O.
– Zinc sulphate commonly crystallizes as the heptahydrate, ZnSO4.7H2O.

Comparing the number of water molecules:
– Iron sulphate (7) and Copper sulphate (5): Different number.
– Iron sulphate (7) and Zinc sulphate (7): Same number.
– Zinc sulphate (7) and Copper sulphate (5): Different number.
– Iron sulphate (7), Copper sulphate (5), and Zinc sulphate (7): Not all have the same number.

The number of water molecules in a hydrated crystal is specific to the compound and the conditions under which it crystallized. Common hydrated salts often encountered in chemistry include copper(II) sulphate pentahydrate (blue vitriol), iron(II) sulphate heptahydrate (green vitriol), and zinc sulphate heptahydrate (white vitriol).

More similar MCQ questions for Exam preparation:-