Question

Which of the following forms the base of talcum powder?
A.Zinc stearate
B.Sodium aluminium silicate
C.Magnesium hydrosilicate
D.Chalk

Answer 1

Hint: Talcum powder is commonly used as a household cosmetic. It absorbs moisture as it finely divides power having a large surface area. It keeps skin dry and helps in preventing rashes.

Complete step by step answer:
-Talcum powder is made up of talc. It is a mineral which is composed of hydrated magnesium silicate and the constituent elements are magnesium, silicon, and oxygen. The chemical formula or representation of talc is \[M{g_3}S{i_4}{O_{10}}{\left( {OH} \right)_2}\].
Talc is mostly deposited in the metamorphic rocks of convergent plate boundaries. It is obtained from two processes. It is found to deposit when heated waters carrying dissolved magnesium and silica react with dolomitic marbles. In the second way the production of talc is obtained when heat and chemically active fluids alter rocks such as dunite and serpentinite.
-Zinc stearate is soap and is produced using zinc metal and "salt" of a fatty acid. It’s texture is white solid which is lyophobic that repels water. It is soluble in aromatic solvents like benzene and chlorinated solvents and insoluble in polar solvents. It is used as a releasing agent and lubricant which can prevent other materials from bonding to the surface.
-Sodium aluminium silicate as the name indicates is the compound of sodium, aluminium and silica. Actually they refer to a series of compounds containing the oxides of sodium, aluminium and silica along with water. They are used to keep the contents of a container dry and also used as synthetic zeolites.
-Chalk is the carbonate of calcium. It is also known as calcite or limestone. The chemical formula is \[CaC{O_3}\]. It is deposited as rocks in marine conditions. Chalk readily crumbles and gets stuck to rough surfaces and hence is used for writing on blackboards. It is also used for making quicklime i.e. calcium oxide (\[CaO\]).
Hence the correct option is C i.e Magnesium hydrosilicate.


Note: Magnesium hydrosilicate is also known as magnesium silicate. The general formula for these salts are \[MgO:XSi{O_2}.{H_2}O\], where X is the average mole ratio of the combination of silicon dioxide to magnesium oxide.