Question

Assertion: The Plaster of Paris is stored in moisture.
Reason: Plaster of Paris sets into a hard mass on wetting with water to form anhydrous
calcium sulphate.
a. Both A and Rare true and R is the correct explanation of the assertion
b. Both A and Rare true and R is the correct explanation of the assertion
c. A is false but R is true.
d. A is true but Ris false.
​

Answer 1

Answer:

Both A and Rare true and R is the correct explanation of the assertion

Answer 2

Question

Assertion: The Plaster of Paris is stored in moisture.

Reason: Plaster of Paris sets into a hard mass on wetting with water to form anhydrous calcium sulphate.

a. Both A and R are true and R is the correct explanation of the assertion

b.Both A and Rare true and R is the correct explanation of the assertion

c. A is false but R is true.

d. A is true but Ris false.

Answer

a. Both A and R are true and R is the correct explanation of the assertion

More to know

Egyptians are credited with discovering Plaster of Paris about 5000 years ago. They prepared is powder by heating gypsum (CaSO, 2H,0) in an open air fire. They used this powder for enting big stone blocks that were used in the construction of monuments.

It is prepared from naturally occurring gypsum (CaSO4.2H20]. Gypsum is crushed to powder and heated at a controlled temperature of 100°C (373 K) for a long time whe molecule of it loses 3/4 of water of crystallisation to form Plaster of Paris.

$\small\tt{CaSo_{4} 2H_{2}o \longrightarrow \: CaSo_{4} \: \frac{1}{2} H_{2}o + \: \frac{3}{2}H_{2}o}$

Properties

• It is a white powder having very fine crystals.
• It gets hydrated, when treated with water with the liberation of a large amount energy, commonly, called heat of hydration

Used

• For creating statues, toys and decorative show piece.
• For panelling roof of house
• For making blackboard chalk
• For making fireproof materials.