Question

On treating roll sulphur with an aqueous solution of calcium hydroxide :
Options-
(A) plastic sulphur is prepared
(B) milk of sulphur is prepared
(C) rhombic sulphur is prepared
(D) roll is prepared

Answer 1

Hint: An attempt to this question can be made by understanding the type of compound roll sulphur is. Now determine the action of calcium hydroxide on roll sulphur. The calcium hydroxide once boiled with sulphur; it is separated from the precipitate using a dilute acid. The precipitate obtained contains sulphur and is the correct answer.

Complete answer:
Sulphur is considered as a chemical element with the symbol S and atomic number 16. It is abundant, multivalent as well as non-metallic. Under normal temperature and pressure conditions, sulphur atoms form cyclic octa atomic molecules.
Elemental sulphur being the 10th most common element by mass in the universe is a bright yellow, crystalline solid at room temperature.
Sulphur present in the form of rods or sticks made by casting the obtained molten sulphur is commonly called roll sulphur.
When sublimed sulphur is boiled with lime water i.e. calcium hydroxide, the lime is removed from the precipitate formed by washing it with dil. HCl. The precipitate is called the milk of sulphur and is used for treatment of various skin orders.
From the above statements we can conclude that on treating roll sulphur with an aqueous solution of calcium hydroxide, milk of sulphur is obtained as the product.

Therefore, the correct answer is option (B).

Note:
Dilute HCl removed the existing calcium hydroxide from the solution by performing a neutralisation reaction. Calcium hydroxide is neutralised by hydrochloric acid to form water. Water does not interfere with the precipitate formed.