Tag: some important compounds of magnesium and calcium

Questions Related to some important compounds of magnesium and calcium

On the basis of following features identify the correct option:
I. It is stored in air-tight bags.
II. It is used in surgical bandages for setting fractured bones.

chemistry the s-block elements (alkali and alkaline earth metals) some important compounds of calcium some important compounds of magnesium and calcium compounds of s block elements

  1. Plaster of paris

  2. Gypsum

  3. Dead burnt plaster

  4. Both A and B

Show answer
Correct Option: A
Explanation:

Plaster of Paris is stored in air-tight bags because in presence of moisture it changes into gypsum.

plaster of Paris is used in surgical bandages for setting fractured bones because it help in immobilizing of broken bones while they heal.

Plaster of paris should be stored in a moisture proof container because:

chemistry the s-block elements (alkali and alkaline earth metals) some important compounds of calcium some important compounds of magnesium and calcium compounds of s block elements

  1. it absorbs moisture from the atmosphere and becomes hard

  2. it cannot be stored in plastic

  3. it will change its colour

  4. it will become soft

Show answer
Correct Option: A
Explanation:

Plaster of paris is calcium sulphate and addition of water of crystallization to it leads to formation of gypsum which becomes hard material. It should be stored in water proof container.
${ CaSO } _{ 4 }\cdot \dfrac { 1 }{ 2 } { H } _{ 2 }O+\dfrac { 3 }{ 2 } { H } _{ 2 }O\rightarrow { CaSO } _{ 4 }\cdot 2{ H } _{ 2 }O$

State True or False.
Setting of cement is an endothermic process.

chemistry the s-block elements (alkali and alkaline earth metals) some important compounds of calcium some important compounds of magnesium and calcium compounds of s block elements

  1. True

  2. False

Show answer
Correct Option: B
Explanation:

When water is mixed with cement to form a paste, reaction starts. In its pure form, the finely ground cement is extremely sensitive to water. Out of the three main compounds, $C _3A, C _3S \ and \ C _2S$, reacts quickly with water to produce a jelly-like compound which starts solidifying.


The action of changing from a fluid state to a solid state is called setting and should not be confused with hardening, which is a exothermic process.


So the statement is False.

Hence option B is correct.

The mixture of $MgCl _2$ and MgO is called:

chemistry the s-block elements (alkali and alkaline earth metals) some important compounds of calcium some important compounds of magnesium and calcium compounds of s block elements

  1. Sorrel cement

  2. Mixed salt

  3. Portland cement

  4. Magnesium oxychloride

Show answer
Correct Option: A
Explanation:

When magnesium oxide reacts with magnesium chloride it forms Sorrel cement.

Portland cement is manufactured by using:

chemistry the s-block elements (alkali and alkaline earth metals) some important compounds of calcium some important compounds of magnesium and calcium compounds of s block elements

  1. Limestone, clay and sand

  2. Limestone, gypsum and sand

  3. Limestone, gypsum and alumina

  4. Limestone, clay and gypsum

Show answer
Correct Option: D
Explanation:

Portland cement is the most common type of cement general use around the world, used as a basic ingredient of concrete mortar, stucco and most non-speciality grout. It developed from other types of hydraulic lime in England in the mid 19th century and usually originates from limestone. 


It is a fine powder produced by heating materials in a kiln to form what is called clinker, grinding the clinker, and adding small amounts of other materials. Several types of Portland cement are available with the most common being called ordinary Portland cement (OPC) which is grey in colour, but a white Portland cement is also available.

Portland cement is manufactured by using Limestone, clay and gypsum.

The main constituent of cement is:

chemistry the s-block elements (alkali and alkaline earth metals) some important compounds of calcium some important compounds of magnesium and calcium compounds of s block elements

  1. $SiO _2$

  2. CaO

  3. $CaSO _4$

  4. $Al _2O _3$

Show answer
Correct Option: A
Explanation:

Hydraulic cement are made up of a mixture of silicates and oxides in the form of silicon dioxide. It is responsible for the mechanical properties of cement.

The main raw materials required for the manufacture of portland cement are:

chemistry the s-block elements (alkali and alkaline earth metals) some important compounds of calcium some important compounds of magnesium and calcium compounds of s block elements

  1. limestone and clay

  2. limestone and gpsum

  3. limestone and calcium chloride

  4. limestone and silica

Show answer
Correct Option: A
Explanation:

It consists of calcium silicates and the ratio of calcium oxide to silicon dioxide is not less than 2. It consists of MgO not more than 5% by mass.

Manufacture of which of the following does not require limestone as a raw material?

chemistry the s-block elements (alkali and alkaline earth metals) some important compounds of calcium some important compounds of magnesium and calcium compounds of s block elements

  1. Quick lime

  2. Baking soda

  3. Glass

  4. Plaster of Paris

Show answer
Correct Option: D
Explanation:

Plaster of Paris is prepared by gypsum. 

Which of the following is/are constituents of cement?

chemistry the s-block elements (alkali and alkaline earth metals) some important compounds of calcium some important compounds of magnesium and calcium compounds of s block elements

  1. $SiO _2$

  2. $Al _2O _3$

  3. $CaSO _4$

  4. All of the above

Show answer
Correct Option: A
Explanation:

Portland cement consists essentially of compounds of lime (calcium oxide, $CaO$) mixed with silica (silicon dioxide, $SiO _2$) and alumina (aluminum oxide, $Al _2O _3$). 

The main raw materials required for the manufacture of portland cement are:

chemistry the s-block elements (alkali and alkaline earth metals) some important compounds of calcium some important compounds of magnesium and calcium compounds of s block elements

  1. limestone and clay

  2. limestone and gypsum

  3. limestone and calcium chloride

  4. limestone and silica

Show answer
Correct Option: A
Explanation:

The raw materials needed to produce cement (calcium carbonate, silica, alumina and iron ore) are generally extracted from limestone rock, chalk, clayey schist or clay.