A sulphate salt of group 2 element of the periodic table is a white, soft substance, which can be moulded into different shapes by making its dough. When this compound is left in open for some time, it becomes a solid mass and cannot be used for moulding purposes. Identify the sulphate salt.

White paris

No worries! We‘ve got your back. Try BYJU‘S free classes today!

Plaster of paris

Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses

Calcium hydroxide

No worries! We‘ve got your back. Try BYJU‘S free classes today!

Calcium carbonate

No worries! We‘ve got your back. Try BYJU‘S free classes today!

Open in App

Solution

The correct option is B Plaster of paris
Calcium belongs to group 2. Calcium sulphate is a white soft substance. It is known as Plaster of Paris, which can be moulded into different shapes by making its dough.
When Plaster of Paris is left for some time in open, it turns into solid mass because of reaction with moisture present in the atmosphere. The solid mass so formed is known as gypsum and cannot be further used for moulding.
$C a S O_{4} . \frac{1}{2} H_{2} O + 1 \frac{1}{2} H_{2} O \to C a S O_{4} . 2 H_{2} O$
Plaster of Paris Gypsum
(Soft) (Hard mass)
(Sulphate salt)
The above said group 2 element is calcium and sulphate of that element is Plaster of Paris. Plaster of Paris shows such behavior because of presence half water molecule as water of crystallization. When it is left open for some time, it absorbs moisture from the atmosphere and forms gypsum, which is a hard solid mass.

Suggest Corrections

Similar questions

Q. Question 47.
A sulphate salt of group 2 element of the periodic table is a white, soft substance, which can be moulded into different shapes by making its dough. When this compound is left in the open for some time, it becomes a solid mass and cannot be used for moulding purposes.
Identify the sulphate salt and why does it show such a behaviour ?
Write down the reaction involved.

Q. A student requires hard water for an experiment in his laboratory which is not available in the neighbouring area. In the laboratory there are some salts, which when dissolved in distilled water can convert it into hard water. Select from the following groups of salts, which when dissolved in distilled water will make it hard.
(a) Sodium chloride, Potassium chloride
(b) Sodium sulphate, Potassium sulphate
(c) Sodium sulphate, Calcium sulphate
(d) Calcium sulphate, Magnesium chloride

A metal salt (M) on reacting with sodium hydroxide forms sodium sulphate and a gelatinous white precipitate of a metal hydroxide. The precipitate is soluble in excess of sodium hydroxide. Identify M.

Q. When a blue coloured copper salt is heated strongly, it forms a white copper salt. The white copper salt can be reconverted into blue copper salt by adding a liquid X.
(a) Write the formula of blue copper salt.
(b) Write the formula of white copper salt.
(c) What substance is lost when blue copper salt is converted into white copper salt?
(d) Name the liquid X.

(a) Why does common salt get wet during the rainy season ?

(b) How can this impurity be removed ?

(d) Name two crystalline substances which do not contain water of crystallisation.

Join BYJU'S Learning Program